Strategies and Technologies in Forensic Science

Forensic science comprises applying scientific principles and approaches under the domain of law and legislation aiming for the execution of justice through providing valid evidence that can confirm the location of the committed crime and the scenario that has been followed to commit the crime.

Forensic science is serving two main tasks, analysing the physical evidence, and providing the resultant information to the court (Kirk, 2009). The main principles concerned with the forensic science are the identification and the interpretation of the physical evidence. In fact, the binary combination of science and technology are representing as the independent witness in the criminal or the civil aspects (Saferstein, 2013). Science and technology are having a close term interference, in fact, the most development of the forensic science is depending on the parallel development of the technology in various science fields (Tilstone et al., 2013). The provided supporting evidence must be strong and valid enough to be utilised in the legal procedures at an elevated level. The long-standing forms of forensic physical evidence including fingerprints, bloodstains, hairs, fibres, soils, and DNA, which can provide a high degree of the scientific certainty, also, to determine that evidence came from one source. In addition, to identify of a sample of origin to a source or sources, of known origin to exclusion of all others based on the analysis of evidence (Kiely, 2005).

Physical evidence is having a critical importance throughout the criminal investigation, due to the fact that the information provided by the victims, suspects, and witnesses are considered as incomplete and inaccurate. For addressing the limitation of the testimony, the investigators are implementing a comparison with the interpreted statements of the physical evidence(Council, 2014).

The crime scene investigation schemes are including evidence identification, collection, preservation, and transportation, in addition, all the necessary tests that aid in proving or disproving the characteristics of samples. The conducted forensic laboratory analysis might provide a comprehensive platform for characterisation and comparison of the questioned source and the known source samples.

Throughout the investigation process, investigators might provide an alternative interpretation of analyses, with the derivatization of new conclusions(Council, 2014).

According to Klinkner 2009, the basic principles of the forensic science methodological approach are:

• Determination and understanding of the information and evidence that could be spotted at the crime scene.
• Following valid procedures for collecting and recording evidence.
• Implementing the evidence-testing phase according to the standards.
• Providing the evidential requirements for the court judgement (Klinkner, 2009).

1.1.1 The importance of forensic sciences

The forensic science is encompassing a vital part of the reconstruction of the crime scene by using various disciplines including Pathology, Anthropology, Microbiology, Toxicology, Chemistry, etc. The forensic science can provide a supportive evidence in regards to the details of the crime scenario including the crime approach, the location, and the time of the committed crime. Furthermore, the implementation forensic science approaches and the relevant technology exhibit a remarkable usefulness in investigative cases involving missing people, whether they are crime victims of or wanted criminals. Additionally, in regards to the oppression, the mistaken victims, and the relevant forensic cases, the mainstay of issuing the verdicts under the law legislation of attaining justice is based on the forensic scientific evidence in the corresponding crime scene following various scientific and medical approaches (civil and criminal)(Fisher and Fisher, 2012).

Forensic science includes several disciplines from biology to E-crime investigation. A list of different forensic sciences is reported as followed:

Forensic Archaeology is concerning the scope of determining the cadaver location and the recovery of the geophysical surveying techniques, moreover, applying photo-documentation and imaging throughout the forensic investigation.

Forensic Anthropology deals primarily with the identification and examination of human skeletal remains (Byers, 2015).

Forensic Ballistics is a scientific domain, which allows the rational application of ballistics for serving scientific purposes, aiming for the attenuation of justice. This heterogeneous discipline of science is availing a major fundamental task which is the restructuring of the fatal or no-fatal crime scenario associated with gunshot injuries (Karger, 2009).  Furthermore, this sector is defined as the science of the projectiles motions, in particular with the crimes committed through the monopolisation of firearms (Warlow, 2016).

Forensic Biology, this scope of science is acting as a layout platform, which permits the intellectual application of the life science knowledge and theories into the forensic investigations sessions. The fundamental attention of this science sector has been directed towards the analysis of the extracted DNA samples and the collected body fluids present at the crime scene (AAFS).

Forensic Computer Science this domain of investigation is concerning the scanning of computers and the suspected devices for the purpose of exploring digital data as a main or supportive investigative evidence (Agarwal et al., 2011).

Forensic Entomology is the study of insects, and forensic entomologists use in civil and criminal cases (Amendt et al., 2007).

Forensic Engineering is concerning the investigation of the failure analysis, restructuring of accidents, and discovering the origin of combustion and explosions (Saferstein, 2013).

Environmental Forensics Environmental Forensics is defined as the systematic and scientific evaluation of physical, chemical and historical information for the purpose of developing defensible scientific and legal conclusions regarding the source or age of a contaminant release into the environment (Murphy and Morrison, 2014).

Forensic Graphology s the study and auditing of handwriting, particularly the handwriting associated with characteristic cases such as ransom notes, poison pen letters or blackmail demands (Oliveira et al., 2005).

Forensic Odontology is involving the extensive study of teeth aiming for providing information about identification and age estimation. Moreover, this scope of science is concerning the investigation of the bite marks associated crimes (Saferstein, 2013).

Forensic Pathology is applied aiming for investigating the causes of unnatural, unexplained, and brutal death through the implementation of inclusive examination of the body and its remains (Rowlinson, 2015, White, 2010).

Forensic Photography is a fundamental element of crime scene investigation, especially for the documentation purposes. Forensic photographers are responsible for recording the crime scene through photographic techniques and approaches (Osterburg and Ward, 2010).

Forensic Psychology is an area in which the relationship between human behaviour and legal proceedings is examined (Saferstein, 2013).

Forensic Toxicology is the study of the effects of extraneous substances such as poisons and drugs in the body (White, 2010).

Depending on the type of the crime, all these forensic sciences disciplines are functioning collectively aiming for performing a comprehensive investigation and reconstructing various crime scenarios for accomplishing the prime aims, justice restoration and culprit condemnation.

1.1.2 Definition of crime

A crime is something that is against the law, and it is any an illegal and incorrect action, which is defined by the law as an offence and for which punishment is prescribed. Accordingly, there are four elements which are considered as the base of the crime events, namely, legality, conduct, unlawfulness and guilt  (Coetzee, 2009, Douglas et al., 2013).

1.1.3 Crime Scene

A primary crime scene is a location where a crime occurred, and where the majority of physical evidence can be found. However, the scene of a crime can be any other places or any other things, which contain physical evidence related to the committed crime. For instance, the vehicle used by the suspects to and from the scene might also contain physical evidence related to the conducted crime, the vehicle will be considered as a necessary area of investigation. Also, other areas needed to be investigated including the residence place of the suspect, searching for robbed items, weapons, burglary tools, any tools that might be exploited to commit the crime, or any other evidence that can be found, all are defined as a secondary crime scene (Coetzee, 2009).

A secondary crime scene has to be processed in the same way as the primary crime scene to collect the physical evidence. A crime scene can be very small or limited, such as the back seat of the car where the sexual abuse occurred for example, or only one room in the house. Also, it can be wider, like the entire of the house or outside the house (street, garden, etc.) (Dutelle, 2016). The crime scene is the initial starting point for the investigation cascade to take place, through the collection of the evidence that can aid in the identification of the criminals (LeMay, 2011). Additionally, the comprehensive investigation of the crime scene can allow the logic creation and the reconstruction of the committed crime. Significantly, the investigation process of the crime scene must follow a detailed systematic approach (Bostanci, 2015).

A crime scene can be also classified as following: (Lee and Pagliaro, 2013).

• Type of crime (murder, robbery, sexual assault).

• Physical location (indoor, outdoor).

• Physical condition (buried, underwater).

• The boundaries of the scene (house, computer, car).

• The appearance of the crime scene (organised, disorganised crime scene).

• Activity (active, passive scenes).

• Size of the crime scene (wide, macroscopic, microscopic scene).

1.1.4 Evidence

The evidence is defined as any information or objects submitted legally to the court as a leading proof of the discovery and the confirmation of the truth of any alleged and suspected mater of facts under investigation. Moreover, under the forensic science context, the evidence is synonymous with the exhibit in legal terms. The evidence is defined as any item or sample collected from the crime scene as a result of the investigation process, including any objects, biochemical or chemical substance, marks and traces such as swabs, whole objects, fibre, debris, fingerprint, and footprints or tires, etc. that provide information about the investigated crime (Tilstone et al., 2013).

The primary sources of physical evidence are the victim, suspect, and crime scene, in addition, the secondary sources include the residence place or any places related to the suspect (Douglas et al., 2013). The exploration and examining of evidence can support the forensic investigation in variable manners; for instance, trace an illegal substance, identification of the remains, or the reconstruction of the crime scenario. These investigative approaches can be implemented utilising tools and techniques aiming for the identification, collecting, analysis, data interpretation, and evidence preservation. Generally, evidence cites data or items that can be exploited in the court to be considered by the judges and juries(Lee and Pagliaro, 2013).

1.1.4.1 Forensic evidence

The science area of application in criminal law usually concerns evidence collection, analysis, and interpretation of information. Due to the complexity of the crime scene environment, different scopes of science have to be used simultaneously (Kiely, 2005). In order to reconstruct the criminal events, various kinds of evidence can be collected and thoroughly analysed. In terms of the accepted legal characterisation, forensic science evidence can be divided into two kinds as follows:

• Testimonial evidence, which is the evidence provided in the form of statements made under oath.

• Real evidence, is based on the examination of exhibits, which can be in a wide area such as a house, or small as fibre, or as fleeting as an odour, or as obvious as the explosion scene.

Forensic evidence can be classified depending on their utilisation throughout the investigations (Table 1) (Tilstone et al., 2013).

Corroborative Supports a hypothesis but could arise for other reasons Fibers on the clothing of the suspect that could come from the victim clothing

Additionally, evidence can be classified into other two essential categories as follows:

Direct evidence; includes eyewitness statements or recorded video by police cameras. In court, direct evidence involves testimony by a witness about what that witness personally saw.

Circumstantial evidence; is an indirect evidence that can be used to reconstruct the criminal event but not in direct trend. Moreover, the circumstantial evidence may provide the relation between the crime scene and the suspect. The nature of this evidence could be physical or biological nature, the physical evidence includes tool marks, or impressions such as fingerprint, footprints, and tire impression. (Fig 1).

Moreover, physical evidence includes fibres, weapons, and bullets, etc. While the biological evidence including body fluids, hairs, parts of plants, and natural fibres. Most of the collected physical evidence, except the fingerprints, is aiding the reduction of the numbers of the suspects. In addition, the biological evidence might usually limit the suspects to a small group, or sometimes reduce them to the most likely individual (Ramsey, 1996).

Figure 1. Evidence classification in two main types

List of some common physical evidence with the commonly associated forensic analysis is listed as following:  (Kiely, 2005, Layton, 2006, Schiro, 2007).

• Shells (Ballistics).

• Signs of teeth (biting) bite marks.

• Fingerprint.

• Fragments of glass.

• Shoes (footprint).

• The impact of the wheels of vehicles.

• Trace evidence.

• Body fluids (DNA analysis and patterns of blood).

• Paint (Analysis of paint flakes).

• Marks on the tools (analysis crush, scratch and digging).

• Hair (All analyses of hair (human – animal).

• Fibres (All analyses of fibres (natural – Industrial).

• Fingerprints.

• Firearms.

• Documents (Forgery (analysis of documents).

• Soil and dust.

This kind of evidence is questioned by the AAFS validation committee.

1.1.5 Crime scene investigation

Crime scene investigation is an important area in forensic science, it is the first step of the criminal investigation process after conducting the crime scene analysis and collection and submission the physical evidence to the relevant forensic laboratories. Crime scene investigation is not a mechanical process, but a sequence of steps that allow the reconstruction of the crime scene. Scene processing is the term applied to describe the sequence of steps and the proper measurements taken to investigate a crime and to reconstruct the circumstances of the crime, through the identification of the events and collect the physical evidence that can lead to the identification of the offenders (Gardner, 2011). Crime investigation usually begins at the place where the crime was committed. The area has to be secured for preventing the destruction of crucial physical evidence and preserve any useful information that can lead investigators to link the perpetrators to the victim. The size of the area to be secured varies with each crime, and a series of protocols prepared to secure and protect evidence should be followed (Fish et al., 2013). The crime scene investigation is more than the careful and attentive processing, documentation, collection and packaging of the physical evidence, it is the integration of all the formerly mentioned elements within the forensic processes. Nevertheless, the crime scene investigator or forensic scientist ability to identify the potential various physical evidence is the foundation and base of all the forensic investigations.

The following recognition of physical evidence besides the identification of the probable source of the evidence is the next step. Actually, the crime scene investigations are the first step towards understanding and establishing what, when, where and how the crime happened as well as the suspects involved in the crime (Lee and Pagliaro, 2013).

1.1.5.1 The process of crime scene investigation

Processing a crime scene is considered as one of the most critical aspects of the effective criminal investigations. Processing and managing the crime scene has been viewed as a technical discipline (Julian et al., 2012).

A crime scene investigation identifies the cascades of events, which have been taken place and led to the committed crime through the careful organisation, documentation, collecting, preserving, interpreting, and reconstructing the physical evidence at the crime scene. Moreover, the objective of the examination of the physical evidence is to provide supportive information to the investigation process. From the intersection and the positive collaboration of these objectives, a proper scientific crime scene investigation can be obtained and accomplished (Julian et al., 2012).The investigator processes the scene in a logical order by following the requested various stages (Gardner, 2005) (Fig 2).

Figure 2. Schematic representation the process of crime scene investigation.

1.1.6 Crime scene documentation

Documentation is the first step in the crime scene investigation process and the reconstruction of the crime (Fisher and Fisher, 2012). Documenting the scene begins with the first responding officer, for any class of cases, whether it is a burglary, assault, accidental death, etc. The crime scene must be documented after conducting an extensive evaluation by the preliminary scene survey. Prior to any shifting or moving or even touching of items present in the crime scene, the whole scene must be fully documented to ensure a permanently preserved recording of the scene in the first founded initial condition.

Thus, the main aim of the documentation process is to record and to preserve the situation of the crime scene and the relation between the physical evidence found in the scene. Moreover, to link the physical evidence with the crime scene status when it was observed by the examiner (Dutelle, 2010).

The documentation of the crime scene is the most time-consuming activity among the investigation cascade and requires the investigator to remain organised and follow a systematic approach throughout the process for more comprehensive and complete documentation process and more accurate and defensible the reconstruction can be (Scott, 2009). In the documentation phase for processing the crime scene, all functions have to be in correspondence and to be consistent in depicting the crime scene. Consequently, the fully documented crime scene permits the ability of the investigators to perform the effective reconstruction of the crime event and deliver it to the courtroom. There are different methods to document a crime scene such as description, notes, printed forms, sketch, 2D drawing, 3D-models, photography, and videotapes. The documentation is important to create a detailed record of the scene, evidence recovered, and actions, which have been taken place during the search of the crime scene (Abu Hana et al., 2008). However, the four major steps of the documentation process are noted recording, videography, photography, and sketching. All of these four steps are necessary to be implemented and none can perform as an adequate substitution for the other. Any type of demonstrative evidence must be verified by authenticity, accuracy and identification (Gardner, 2011). The accurate recording of crime scene details is crucial for several reasons: first, it will provide investigators with unaware information; furthermore, it will provide an assisted in the reconstruction of the scene by the court. Nowadays, high geometric accuracy 3D crime scene reconstructions techniques are frequently used for forensic investigations, since evidence gathered with topographic and photogrammetric devices can be more compelling for juries and allow investigators to virtually revisit a crime scene (Agosto et al., 2008).

Furthermore, to ensure the integrity of all evidence recovered from a crime scene and demonstrate the credibility of a crime scene investigator, it is important to make extensive records. This requires the completion of several interrelated documents for all of the recovered items (Scott, 2009). In the other hand, errors can be raised from the incomplete documentation; therefore, all aspects of the scene have to be documented through the crime scene photography, ensuring that all critical evidence has been documented. Adherence to a systematic photographic technique as well as a standard scene processing model will significantly eliminate possible errors (Gardner, 2011).

However, the purpose of the crime scene documentation is not just to document the physical evidence, but also to document the whole scene. The term entire scene including the unreachable points in the walls, ceilings, and objects. The lack of photo-documentation of these areas may result may result in claims by lawyers of evidence that was present on the surfaces that the photography “missed.” For an accomplishing a successful photographic documentation, the entire scene must be completely documented through photo capturing, in both cases of presence or absence of evidence to prove that nothing was there (Dutelle, 2010).

There are multiple reasons, which confirm the significance of documenting the crime scene, one of the prime reasons is to provide a permanent record of the crime scene in the initial founded state to be used during the investigation, to function as a reminding tool for the investigators or witness, also, in court if the case culminates in a trial. An additional reason is to provide a platform for counting the steps followed during the processing of the crime scene. Furthermore, documenting the degradable physical evidence in which the preservation process is problematic until its recovery from the scene (Jackson et al., 2011). In addition, the essential tools which aid in the effective documentation of the crime scene during investigation including Photographs, sketching, videography and the CSI’s reports  (Fish et al., 2014).

1.1.6.1 Reports or Notes

Extensive recording of notes and observation for all physical evidence recovered from the crime scene is considered as a significant aspect, including the location in which the physical evidence has been discovered, who has collected the evidence, at which time, and a description of the item itself. Additionally, overall notes regarding the scene should be recorded, including the surrounding environmental conditions, and any other relevant details. Sketches are generally utilised to provide an illustration in regard the locations, dimensions and significant object orientations founded at the scene, also the relevant measurements (Fish et al., 2014).

A chronological order for the documented notes and observations is important, and it must be exhibiting the lack of any analytical findings, conclusions, or personal suggestions. Subsequently, the documentation areas of the investigation process are only restricted towards the crime scene observed facts, the documented notes are adaptable to any updates throughout the investigation process. In addition to the observed notes, there are vital factors needed to be recorded such as the date and time indicators (e.g., newspapers, Mail), general descriptions of the scene and surrounding area, open doors and windows, any person who was present at the crime scene, victim and witness statements, odours or any characteristic smell and lighting conditions (Miller, 2013).

1.1.6.2 Sketches

Sketches are utilised along with the images and reports to document the crime scene. A crime scene sketch is a simple drawing that exactly demonstrates the state of a crime scene, the position of the relevant items, and the relationship of the items (Saferstein, 2013). These must include the real measurements, without the urgent need to reach to the architectural drawing scale. Furthermore, for courtroom presentation, the hand-drawn sketches can be converted using computer programs such as CAD, which provide a dynamic, professional appearance to the sketches (Dutelle, 2010).

One of the main advantages of a sketch is that it can cover wide spaces and scenes; also, it can be instantly sketched to give a clear diagram of the scene with the accurate orientation. Actually, sketching acts as a complementary aid to the photographs and videos of the crime location to obtain the proper dimensions of the crime scene as both (pics and videos) can distort those measurements. Usually, the usage of the sketch gives a complete and detailed state of the crime scene, whereas the two dimensions photograph does not show the accurate measurements of objects and between them. Moreover, the sketch is able to represent the whole scene in one paper (Miller, 2013).

Rough sketches and final sketches are the two types of sketches used for documentation of crime scene (Fig 3) (Saferstein, 2013).

Figure 3.  (A) Example of a rough sketch (B) final sketch (C) Example of a final sketch using CAD program

The sketch is considered as an important aspect of the documentation of the crime scene as it describes the physical facts accurately. It also provides the ability to document the exact site and present the relation between the existing objects and the observed evidence at the crime scene. In addition, it can be a useful tool in the creation of the overall picture of the crime scene for the distanced observers such as judges, juries, witnesses, and others. Furthermore, it can provide a permanent piece of court acceptable record of the crime scene. Additionally, it can thoroughly support the preparation of the investigative reports by the investigators and provide help for the clear presentation in the court by the case presenters (Layton, 2006).

1.1.6.3 Videography

Scene documentation also includes videography, especially in murder cases.  Video recordings can provide supportive information for the layout of the crime scene, such as the specific time intervals, which was required to move from one location to the other, and how many turns were presented. Once the investigation has proceeded further, detection of forgotten things and errors (Layton, 2006). Illustratively, during a video walk-through the crime scene, the crime scene investigator captures the whole crime scene and the areas around the scene from all the possible angles and record a continuous audio narrative (Fish et al., 2014).

1.1.6.4 Photography

Photography is the most important of the crime scene documentation techniques, by producing a lasting visual record of the crime scene and discovered evidence (Scott, 2009). Photographs capture time in a unique way; they provide a static representation of a scene, reflecting its properties at a specific time interval. The photography is the essential way in the documentation process and an important tool in the field of crime scene investigation. Photos are captured of the overall scene as soon as possible to record the scene as it is observed before anything is handled, moved or added to the scene (Pastra et al., 2003).

Photos cover the condition and orientation of the overall scene, the location, and if possible, the relationships between different areas in the scene as well as to the various items of evidence found at the scene (Suboch, 2016). Photo documentation allows the viewer to observe the necessary detail of specific items found in the scene (Miller, 2013).

Collectively, all that can be achieved by three main kinds of photos, which crime scene investigators need for crime scene documentation as follows: (1) Overall scene photos showing the possible view of the scene. (2) Evidence-establishing or mid-range photos presenting the relation between the items. (3) Evidence close-up  (Layton, 2006).

Close-up photos are usually captured of the items that include a serial numbers or tags. The following photo with the addition of a measuring tool is captured for the same items; these photos help the analytical process. In addition, special techniques of photographs such as panoramic photography are used to capture the large scene (Layton, 2006). The human visual is nearly 180 degrees, but that of a standard 50-mm camera lens is approximately 80 degrees. Photos are taken and merged together using different software to present a complete view (Fisher and Fisher, 2012).

1.1.6.4.1 Capturing photos of the scene

The photos can provide supportive evidence and information about the crime scene only when the images capture the whole scene. In another hand, the images can be misleading due to the type of imaging capture process (perspective projection, lens distortions, etc.).

The main objective of capturing the overall photographs is to recover the general condition and layout of the scene. The photographer always seeks to capture the whole scene including the most visible landmarks (e.g., doors, furniture, bodies), and the original condition of the scene prior to the significant change. Therefore, overall photographs are always the first photos taken (Suboch, 2016).

Overall photographs normally are used to capture the room or the scene. Usually, it is believed that taking photos from the opposite corners of the scene is a good practice for the overall photographs capturing (Fig 5). Through repeating this process for each corner of the scene, which is resulting in four photos that provide overlapping coverage of the complete scene. In addition, wide-angle lenses (e.g., 28 mm lens) are often used to allow the photographer to capture a wider view in a single photo. The ability of the photographer to capture wide areas of the crime scene can be enhanced through the utilisation of extreme wide-angle lenses, although, as the field of the view increases, more peripheral distortion might occur. Therefore, a wide-angle lens is not suitable for crime scene and evidence photography (Gardner, 2011).

Figure (4) summarises three different kinds of photos capturing form different scenarios. Panoramic images are also affected by similar problems. In fact, manual modelling of the scene is difficult and may not result in a realistic model (Bostanci, 2015).

Figure 4. The directions of photos taken for different cases of capturing the object or the scene.

Figure 5. Overall photographs are exposed so they overlap each other. A typical procedure is to go to the corners of a room and take a photograph in each one, looking to the opposite corner

1.1.6.4.2 Digital Imaging

Digital imaging technology provides the crime scene investigator with powerful new tools for capturing, analysing, and storing records of the crime scene along with the obtained physical evidence (Fig 6). However, these digital imaging tools complement the traditional tools, thus, video and photography still used in crime scene documentation (Mennell and Shaw, 2005).

The advantages of digital images include instant access to the images, easy integration into existing electronic technologies, the bypassing of the need for expensive film processing equipment and darkrooms. The disadvantage of using digital image technology is issues of court admissibility due to the easy image manipulation. However, written and implemented policies and procedures for using digital images can eliminate the disadvantages. The law enforcement community agrees that digital imaging in crime scene documentation can best be used as a supplemental technique and not as a complete replacement of the traditional techniques like sketching and notes (Bostanci, 2015).

Figure 6. Recording of crime scene and evidence using handheld digital camera

1.1.7 Crime scene reconstruction

The reconstruction of the crime scene was evolved during the 1990s as a new aspect of forensic sciences that combines areas from a number of different disciplines. Crime scene reconstruction is the use of scientific methods, physical evidence, and their interrelationships to gain a clear knowledge of the series of events related to the crime (Clemens, 1998). In general, the crime scene examinations are recommended to be performed as quickly as possible, although in some exceptional circumstances a delay in the investigations is approved. This is a result of the nature of the evidence, as it is usually ephemeral and lasts for a very short time. Moreover, the scenes of crime might present a variation in the evidence. This variation stands as an enormous challenge facing the investigators and forensic examiners efforts to record and document the scene details for subsequent analysis. This typically includes detailed measurements by means of photography and videography. Subsequently, investigators create scale drawings of the scene and in some cases they make physical models. The main purpose of reconstructing a crime scene is to obtain accurate information describing the cascade of events surrounding the committed crime using physical evidence, scientific methods, and their interrelationships.    Both the evidence found at the crime scene and the evidence collected during the time of the crime, contribute the reconstruction of the crime scene in four dimensions: width, depth, height and time (Knox, 2012).

Crime scenes can be reconstructed using various levels of detail is correlated to the aim of investigations. A crime scene reconstruction is a process of determining or eliminating the actions that happened at the crime scene by the analysis of the crime scene pattern, in addition, the location and position of the physical evidence, and the result of the laboratory examination of the physical evidence (Lee et al., 2001).

Throughout the recent years, the persistent improvements in technology are followed by a parallel interest in implementing this technological technique to ease the forensic investigation, these techniques such as designing computer graphics software which can simulate the crime scene. This approach can offer several advantages in comparison to the traditional methods, including the creation of a partial realistic view of the scene from different positions and angles, additionally, combining forensic with the computer modelling. Until now, most of the crime scene reconstruction systems provide adjustable 2D and 3D views of Cad models, rendered using standard local illumination techniques. While such systems can be of substantial benefit to investigators, they are not primarily concerned with creating reconstructions that attempt to be realistic (Howard et al., 2000).

The overall all documentation process, including the pictures capturing, recording measurements, and notes, of the crime scene, is deemed to be a problematic process.  Therefore, it is required to assign updated approaches featured with accuracy, details oriented, fast, and capable of preserving, viewing, and preserving the crime scene to the jury. As an out to date example, one of the advances in the useful recent technology in law enforcement is the developing and the adaptation of the high-resolution cameras that poses the ability to capture multiple images during a short period of time. This technique can aid in cataloguing the entire crime scene and documenting most of the details present in the crime scene, thus, considering it as a useful tool for the investigator and for court the presentation. Some cameras are designed to able to capture images in 360 degrees, these cameras are offering a massive ease of utilisation and great flexibility. Furthermore, the laser scanners are more precise of the investigative scene. A permanent visualising record of the entire crime scene can be digitally created through this technology. Additionally, it permits the investigator to review the image immediately after capturing it and allows the proper adjustment to the captured photo. Consequently, the reconstruction of the crime scene has been evolved during the recent years, and becomes an implementation area for imposing the high and sophisticated technologies, such as Total Stations, Panoramic cameras and now 3D Scanners (Fig 7), instead of the outdated techniques, such as the tape measure and recording information and data in a paper forms (Keith W, 2015).

The process of crime scene reconstruction should be performed optimally in a short period of time, thus, time management and arrangement is a problematic factor during the investigation. Additionally, the crime scene is vital entity can provide supportive perception in regards to the crime event cascade, which has been taken place in a specific time interval, and in accordance time unit, second, minutes, hours, and even days or more. Therefore, the prolong recording time can inform about the magnitude of evidence which has been observed and collected thoroughly, also, the sequence of recording is considered as a vital aspect through the documentation (Knox, 2012).

Figure 7. Different approaches used for capture a crime scene. (A, B) outdoor and indoor panoramic images. (C, D) outdoor and indoor Laser scanner generated point clouds (E, F) Sketch up and 3D modelling

1.1.7.1 Stages of crime scene reconstruction

The stages involved in the reconstruction of a crime scene can be summarised in six steps:

• Collection of data: Information or documents belonging to the victim or witnesses, which have been collected from the crime scene.

• Studying and analysing physical evidence, patterns, for determining the number of impressions.

• Experts guess; before taking any action on the evidence, the investigators can access the possible interpretation of the evidence or the subject of the guesswork out of participation in the crime scene.

• Preparing hypothesis, depending on the extracted data upon the examination of the physical evidence, scanning the scene, searching for missing evidence, the interpretation of patterns of fingerprints, tracing evidence, and analysing the results that lead to the formulation of the hypothesis of the reconstruction.

• Investigations, through developing and testing an additional hypothesis aiming for confirming or refusing the overall hypothesis, which can include imposing a microscopic examination, chemical analysis, and other confirmatory tests to the hypothesised concepts.

• Developing a theory, through obtaining additional information in the inquiry in regards to the status of the victim or the suspect, witness accounts and other information about the circumstances of the event. The accurate testing of this hypothesis can be performed through implementing the proper analytical procedure, aiding the formulation of the reconstruction theory in association to the obtained results. In fact, the crime scene and the obtained physical evidence, records, data and witness are the main sources of the information (Bader and Gabriel, 2009).

1.1.7.2 Importance of crime scene reconstruction

The accurate recording of crime scene details is crucial for several reasons; providing the investigators with visual information that they may not otherwise have known about. Furthermore, it will support the scene reconstruction and the clear presenting to the court (Chisum, 2006). Nowadays, high geometric accurate 3D crime scene reconstructions are frequently used for forensic investigations. This is due to the fact that evidence collection with photogrammetric devices can be more compelling for juries and allows the investigators to virtually “revisit” the crime scene (Agosto et al., 2008).

One of the most useful ways to find out the real scenario of the crime is to limit the possibilities that created the crime scene or the evidence as found. The integrity of the crime scene is the main driver for reconstructing the crime (Lee et al., 2001). Moreover, the reconstructing of the crime scene is one of the major ways to preserve the integrity of a crime scene.  It is different from re-creation or criminal profiling. Recreation is by replacing the essential things or activities at the scene of a crime according to the original scene documentation. Whereas, re-enactment is by re-ordering the scene of a crime by suspect, witness or another individual depending on their information about the crime. Criminal profiling depends on psychological and statistical analysis of the scene in order to identify the attributes of the suspect, which can be considered as a supportive aspect of the forensic investigation. In spite of that, these analyses are not commonly used in solving crimes. Reconstruction is established on the capability of imposing the accurate observations at the scene, the scientists ability to observe physical evidence and using the logical routes to formulate the theory (Miller, 2013).

1.1.8 3D Reconstruction

In the last years, the generation of 3D models for objects has become a topic of interest for several researchers. Particular attention has also been paid to the reconstruction of realistic human models, which could be employed in a wide range of applications (Pollefeys, 1999). Compared with a conventional photography, the 3D reconstruction of the crime scene is not restricted to the idea of acquiring an album of photographs with a 360-degree image of view, but it is an integrative process composing of a variety of scene elements, which shows the actual place where the crime occurred (Liao et al., 2015).

Crime scene investigation in the three dimensions can be an effective means to a more comprehensive understanding of the details of the crime (Ma et al., 2010). In addition, 3D is a highly effective tool for communicating complex scenarios to a jury and aiding counsel in describing and presenting a situation. Repeatedly this has proved to be an intriguing communication tool. By enhancing the concentration of the jury, clearer descriptions and detail can be retained. In addition, 3D crime scene reconstruction can be considered as a cost-effective approach through the elimination the unnecessary site visits (Se and Jasiobedzki, 2005).

A crime scene reconstruction in three dimensions is developed as an extension of current techniques of crime scene investigation. Developing an accurate 2D model of the crime scene is the first step in a crime scene reconstruction; also, crime scene photography is a basic and important driver to create 3D models. In addition, crime scene investigators collect other data including measurements to help create accurate 3D models. A 3D model is an accurate mathematical representation of the actual crime scene (Sauter, 2011).

Obtaining three-dimensional reconstructions of scenes or objects from images has been recently considered as an interesting area of research in relevance to the computer field and other concerned domains, which are interested in the aspect of the 3D modelling.

However, in all cases, accuracy is the basis that needed to be obtained through exploiting sophisticated devices with high technology, with drawbacks of affordability and the requiring of high expertise specialists (Pollefeys et al., 2000). Nevertheless, obtaining realistic models considered as a laborious and costly task, in addition, in plus to the on-site measurements, the manual restructure of the whole site, the correction, and the utilisation of the additional software can all be a time-consuming task (Remondino, 2011). Although, a consensus of agreements in regards to the best technique which can be implanted for the 3D reconstruction. In general, a supportive range of sensors, laser scanners, presents throughout many applications, the combination and the integration of different recording techniques, in particular when surveying large and complex sites, is the optimum method to be followed, which can ensure the accuracy, the portability, and the low-cost, fast acquisition, and flexibility (Remondino, 2011).

Accuracy: Precision and reliability are key factors of metric surveying unless the work is performed for simple and quick visualisation.

Portability: the portable techniques are the most appropriate due to accessibility issues through many sites, particularly in the absence of electricity, location constraints, etc.

Low cost: with the limited budgets that documentation missions have. The relatively inexpensive 3D methods such as photogrammetry using a digital camera can obtain high-quality information.

Fast acquisition: most sites have limited time for documentation.

Flexibility: Due to the variety and the dimensions of both locations and objects, the used technique should be adaptable to a variety of scales and it should be applicable in a variety conditions (Remondino, 2011).

1.1.8.1 Methodology of 3D reconstruction

Reconstruction of three-dimensional models is needed for various applications utilising various techniques and technologies, although, it considered as a complex process. The reconstructed 3D models can be used in virtual environments for visualising applications, classification and analysis. Some methods of 3D reconstruction are presented as following:

1.1.8.1.1 Handheld devices

Several applicable techniques that can impose throughout the crime scene to aid in defining the location, recording and recovering the physical evidence. The urge of using the technology to aid the investigation is raising throughout the years, in parallel with the introduction and the upgrading of the digital cameras. The utilisation of the specialised digital cameras, as previously mentioned, can support the investigation through documenting the crime scene, briefing purposes, or to create a 3D model (Mennell and Shaw, 2005). The order of photos captured with a digital camera used to create 3D models, and the camera motion is recovered by comparing the key features in the image sequence. Dense stereo matching is performed between the sequential frames. The input photos are used as a surface texture to obtain photorealistic 3D models. However, it requires a prolonged processing time and the outputs of a scaled version of the original object.

Another device is a self-referenced sensor, which consists of two cameras and a cross-hair laser light projector. Frame to frame registration is achieved using a set of fiducials projected with an additional stationary laser system. The system requires a long acquisition time as it can capture only sparse 3D data for each frame and the 3D models do not have a photo-realistic appearance. Additionally, a real-time 3D modelling approach that enables the user to rotate an object and observe a continuous and updated model as the object is scanned. It consists of a 60Hz structured-light rangefinder and a real-time variant of ICP (iterative closest points) for alignment. It is limited to the outside-looking-in case and does not acquire colour. In addition, the Model Camera, which is a low-cost hand-held scene-modelling device. It consists of a digital video camera with 16 laser pointers attached to it. Model Camera acquires 16 depth samples per frame and registers the frames using depth and colour information. The surfaces are approximated with a few quadratics and this approach only works for smooth continuous surfaces ISM utilises stereo cameras to gain 3D data, detect the camera motion and record successive frames together. The resulting models are fully calibrated (allow Euclidean measurement) and have a photo-realistic appearance. The data acquisition and processing takes minutes (Se and Jasiobedzki, 2006).

1.1.8.1.2 3D laser scanner

The 3D laser scanner is a technique that oriented to scan the physical objects; the laser beam is adjusted and projected directly to the object in a closely spaced grid of points. By measuring the time of laser light, which is the time of travel of the laser from the scanner to the physical objects and back to the scanner, the position in three-dimensional space of each scanned point on the object is established. The resultant data will be in a cloud form of points, which consists of thousands of points in three-dimensional space that is a dimensionally accurate representation of the existing object. This information can then be converted into a 3D CAD model that can be manipulated using CAD software, and to which the design of the new equipment can be added (Arayici et al., 2004, Gasser et al., 2001). Terrestrial laser scanners are being used more frequently in the built and natural environment due to their high data acquisition rate, high accuracy and high spatial data density. Though parameters vary from instrument to instrument, acquisition rates vary from 1 to 6 kHz, ranging accuracy varies from 5mm to 25mm (Arayici, 2007). Nevertheless, the problem with a 3D laser scanner is that laser beams projected from the device may not always reflect back to the sensor properly due to the difference in surfaces types. Furthermore, additional parameters to be taken into consideration in relevance to the affordability of the devices and the cost-effectiveness, the range of existing prices deemed to be expensive, in addition,  specialists are needed to run these devices effectively (Bostanci, 2015).

The essential technical characteristics of laser scanner are listed in table 2.  In addition, several required accessories (i.e. laptop, tripod, batteries, and marks) are also shown in Figure 8 (Fernández-Sarría et al., 2013).

Figure 8. Laser scanner accessories required. (A) Leica scan station (B) Aiming mark on tripod (C) Scanned target

1.1.8.1.3 Other methods

A computer software is available to present the crime scenes in two and three-dimensional. In addition, some computer programs have the ability to draw crime scenes to the required scale and have been used to impose drawing movement in shooting scenes to be utilised in the reconstruction of the crime scenes. Moreover, some programs are able to describe the scene in three dimensions similar to video slices. Which can provide a simulated, experience to the viewer to create the crime scene utilising computer graphics. These systems have been used in the courtroom to project the video image onto a screen and to provide an explanation to a jury in regards to the condition and the sequence of events in the crime scene. The software also can be used to describe the crime scene in drawn format depending on the victim or the suspect scenarios (Fisher and Fisher, 2012).

1.1.8.1.4 3D reconstruction using photogrammetry

Butnariu et al (2013) described the process to formulate the proposed methodology (Fig 9)for image-based 3D reconstruction of an object to cover the following steps (Butnariu et al., 2013):

Acquire a set of images: The first essential step in geometric reconstruction using principles of photogrammetry is to obtain a set of images of the object that is intended to be reconstructed. The way in which photographs are acquired is a very important aspect greatly reflected in the quality of the final reconstruction. The object is photographed from different angles, spatially arranged in a circle or arc around the object and each photo must contain about 70-80% of previously captured image content.

Generate a point cloud data from the images: The images from the data set are used to identify the points of interest, and to obtain the 3D coordinates of the object. The process is carried out using a specific framework. Because is a compute-intensive process, using a standalone software framework require a powerful computing system. For obtaining a better sits of results, a cloud of web service has been utilised for serving the scope.

Generate a 3D mesh model: On this step, the resulted point will use to generate a textured 3D mesh. For these step, the free software MeshLab® can be used.

Figure 9. Methodology for virtual reconstruction

Cloud mode: it is a large collection of points that are placed on a three-dimensional coordinate system. Often is intended to represent the external surface of an object, by measure a large number of points on an object’s surface.

Textured mode: it is used for photorealistic visualization of the 3D models (image-based rendering). Texture modelling in its simplest form involves a single texture being mapped onto the surface composed of one or more polygons.

Many modelling tools have a very steep learning curve, so the time required to invest in learning a tool to get even a simple result is often prohibitive.  Among all the web-services packages actually available, 123D Catch by Autodesk is the software that allows improving the result of the 3D scene reconstruction through the manual stitching of matching points on triplets of images and the resubmission of the scene to the service. The used approach underlying 123D Catch technology is well described in (Hsu et al., 2009).

A technique like 123D Catch undoubtedly helpful and it provides the scientists with a good tool for an accurate result. Indeed, there is evidence that 123D Catch technique is capable of producing the same size of data sets, which are comparable to laser scanning. This is significant as these high-resolution data sets are generated at lower costs and with reduced data collection times. In addition, it should be recognised that image-based methods do require significant image texture to be effective and accurate. However, nearly most the photogrammetry services are very fast and easy to use (Erickson et al., 2013).

1.1.8.2 Comparing of some 3D reconstruction web service methods with Autodesk 123D Catch

Due to the development of cloud computing in the last years, several frameworks have developed reconstruction. This review shows the most actual frameworks and compares their features and capabilities (Table 3) (Butnariu et al., 2013).

1.1.8.2.1 Autodesk 123D Catch

Autodesk 123D Catch is a free service offered by Autodesk that uses cloud computing for the reconstruction of 3D objects from images, which is managed through software downloaded from (www.123dapp.com/catch). The management of data is made through a standalone software application installed on the user PC (Chandler and Fryer, 2013). This application allows uploading images, downloading the results, rendering the processed 3D point cloud or mesh, export the result using several 3D formats (DWG, FBX, RZI, OBJ, IPM, LAS). This service can process automatic up to 70 photos in a short time (Butnariu et al., 2013). Furthermore, it is possible to set the origin and the axes of a global reference system. The final result of the reconstruction process is a triangulated surface which can be achieved in three different resolutions: mobile (fast medium resolution mesh), standard (high-resolution texture mesh) and maximum (very high-density mesh). Recently two kinds of applications are available: the web application that allows computing the 3D scene directly online, and the application for the smartphones, iPad or PC which enables the creation and the review of the 3D scene (Bostanci, 2015).

1.1.8.2.2 ARC3D

ARC3D is a free web service that provides a standalone software application for uploading photos to the server system. The application delivers valid results when a number of photos about 70 are used. After processing the images, the results are received by a notification email containing links to the files generated. It contains two types of reconstruction data: pixel maps in a V3D format that can be used for the manual reconstruction of 3D. Mesh from a generated point cloud using MeshLab software of a 3D textured mesh in OBJ format processed by the ARC3D server application (but not accurate), and a low result model for online viewing (Schöning and Heidemann, 2015, Butnariu et al., 2013).

1.1.8.2.3 Hypr3D

Hypr3D (www.hypr3d.com) is a free web service similar to ARC3D that provides only a web interface to upload and download the files. Good results are obtained when 70-80 images are used. The advantage of this approach, compared with ARC3D, is the reduced time of delivering the reconstruction results (about 3-4 hours). The web service delivers two types of geometry: low resolution meshes in a 3D format with JPG textures and a point cloud in PLY format. Also, a high-resolution mesh in STL format can be obtained, but without textures applied (Butnariu et al., 2013).

1.1.8.2.4 My 3D Scanner

My 3D Scanner (www.my3dscanner.com) is a free web service. This service can process up to 100 photos, but for a long time up to 25 hours. The advantage of this application is the high-resolution mesh delivered (up to 1000000 triangles). The drawback is the missing of textures applied to the mesh because it contains only colour information. The result delivered by the application contains an object file for the 3D mesh and a ply for the point cloud (Butnariu et al., 2013).

In addition, some open source reconstruction software has a standalone application as following (Butnariu et al., 2013).

1.1.8.2.5 Photosynth

Microsoft Live Labs developed Photosynth successfully into a web application; it is a web service that is accessible through a Windows Live account on the Photosynth website. Photosynth is a photo visualisation tool that uses the same underlying data (camera positions and points) (Snavely et al., 2008). Users can upload their images to Microsoft’s server and the server will return point clouds. Photosynth enables to create two kinds of 3D products: creating panorama views and synths. The former stitch a set of images together taken from the same point to create a panoramic picture; it creates a view that allows browsing from photo to another photo by using a set of overlapping images. However, it is also able to create a point cloud of the object. By using some toolkits and the results can be exported in different formats (PLY, OBJ, VRML, and X3D) (http://synthexport.codeplex.com) (Brutto and Meli, 2012).

1.1.8.2.6 Agisoft PhotoScan

Agisoft PhotoScan is a low-cost software from Agisoft LLC (www.agisoft.ru) to obtain automatically high-quality textured 3D models, using digital photos of scenes (Agisoft, 2012). The software is based on Multi-view 3D Reconstruction technology and can operate with calibrated and uncalibrated images in both controlled and uncontrolled conditions. PhotoScan has two versions for sale: $179 for a standard version (low-cost) or $3499 for a professional version. This program is executable under Windows operating systems (Kersten and Lindstaedt, 2012). In addition, all data will remain with the users on their personal computers, this software could be operated for the large projects that need around 100 images or more, and the model can be exported for editing in external software. All the processes can be performed with different levels of accuracy and many parameters can be set to improve the final result (Brutto and Meli, 2012).

1.1.8.9.3 Previous studies of 3D reconstruction

The 3D modelling or 3D reconstruction has attracted the interests and the intention of the relevant researchers in the forensic domain during the last few years. A demonstrative review of some previous related studies on the 3D modelling and the 3D reconstruction section have been elucidating in the following table (Table 4).