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Skip to 0 minutes and 14 secondsCrime scenes and TV programmes are usually examined and solved by one of the principal characters with minimal assistance from others. Art does not imitate reality here, and crime scene examination at major crimes is very much a team effort that could involve many people and many different roles. Bearing in mind that we are dealing mainly with the investigation of major crimes, the typical roles that are met by crime scene personnel will include one or more of these-- the crime scene manager, whose role is management of the technical aspects of scene examination and coordination with the SIO. The crime scene examiner. Their role is the discovery and recovery of evidence such as DNA, fingerprints, et cetera, in major and volume incidents.

Skip to 1 minute and 2 secondsNext, there our forensic scientists and specialists who will look at the following-- blood pattern analysis, marks examination, firearms examination. In some jurisdictions, the scene role is restricted to recording. Other jurisdictions assign the complete analysis to scene personnel. And finally, finger marks. Roles and responsibilities for this vary, but most crime scene units conduct at least basic finger mark enhancement, and some conduct mark comparison. Advanced mark enhancement is more often than not the responsibility of forensic laboratory chemists. Some scenes will require specialist investigation. Some of the specialist roles that may need to be included in the team are forensic pathologist, whose role is examination of the body at the scene and post-mortem examination, or autopsy, at the mortuary.

Skip to 1 minute and 57 secondsForensic odontologist, whose area of expertise is examination and comparison of teeth indentation. The forensic chemist, who may be required to attend a scene involving a chemical, biological, radiological, or nuclear incident. CBRN, or who would attend a clandestine drug laboratory. Forensic anthropologist, who examines skeletalised remains. Forensic entomologists, who are experts in insect activity, and can aid in the estimation of time of death from infestation of corpse. Fire and explosion investigators, who can help to determine the cause, origin, and development of a fire. Of all of these roles, that of the crime scene manager, or CSM, is probably most important. We met the CSM when discussing control and the ABC rule. This is illustrated in The Guardian article listed in the resources.

Skip to 2 minutes and 56 secondsAs you've just heard, the CSM is responsible for the conduct of the technical aspects of the investigation and coordination with the SIO. And there are many aspects to this, including assessment, planning and degreeing the forensic approach, and the specific sequence of examinations in individual scenes. Allocating appropriate numbers of personnel to individual aspects of the scene examination, managing the welfare of staff, health and safety risk assessments and implementation of control measures, planning and managing the forensic aspects of post mortem examinations, briefing scene personnel and communicating findings from the scene to the investigation team, advising the SIO on the investigative potential of evidence types, generally and specifically, advising the SIO on the value of using experts in particular fields, such as ballistics, blood patterns, fire investigation, coordination of individual experts within the overall the scene examination, agreeing the forensic strategy with the SIO, maintaining ongoing communication between forensic laboratories, individual experts, and the investigation team.

Skip to 4 minutes and 19 secondsEverything discussed so far can be paraphrased as, how do we make what is present at the crime scene tell us the story of what took place? This is not easy. Only the perpetrator really knows, and as mentioned earlier, even he may not. He may have acted under the influence of alcohol or other drugs. We have to find the things, which is what we have dealt with so far. And then we have to interpret them to recreate what happened, which is what we will close this section with. Probably one of the best role models for a crime scene investigator wasn't a forensic scientist. He wasn't even a real person. It was, of course, Sherlock Holmes. Just think about this.

Skip to 5 minutes and 5 seconds"It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories instead of theories to suit facts." This quote from Arthur Conan Doyle's Sherlock Holmes novel the "The Sign of the Four, A Scandal in Bohemia," captures the essence of crime scene reconstruction. Although we think of Holmes as the master of deduction, in fact, the process is the reverse. It is one of induction, developing a theory based on observations. There is a warning message in the quotation about insensibly twisting facts to suit theories. Good crime scene reconstruction is an intellectually rigorous process akin to the fundamental scientific method of hypothesis development, testing, and refinement, or rejection. This is no easy task.

Skip to 5 minutes and 58 secondsBut we briefly explored a tool earlier, the six W's. These are rooted in the fundamentals of rhetoric, established by the ancient Greeks. To recap, they are what, where, how, who, when, and why. Framing the reconstruction around and the six W's adds rigour to the investigative process because they require factual answers, not yes or no. We will now see how they're used in developing the scene reconstruction. The important connection between the six W's and the Sherlock Holmes quote is that the scene reconstruction must not use them to find evidence that supports preconceived ideas, but it must seek as many answers to each as is reasonable. These then are evaluated as a whole. And the most likely explanation is the starting hypothesis.

Skip to 6 minutes and 56 secondsWe will now look at each in turn. What is first and foremost about establishing criminal content, or corpus delicti. It is also about ensuring that the reconstruction is detailed and accurate. What was the sequence of events at the scene? Does the pattern of blood staining at the scene suggest an unfortunate accident or a violent attack? What was the modus operandi? Does the burglary appear to be one of a series warranting an escalation of the inquiries? Is the nursing home death suspiciously like a previous death? What physical entities were involved? At a fire scene, does the damage indicate an electrical failure, or are there signs of the use of an accelerant?

Skip to 7 minutes and 45 secondsWhat was left at or removed from the scene during the incident? Stolen property, cigarette ends, physical marks, saliva on the neck of a bottle that the perpetrator drank from, and possibly what was the possible motive of the persons involved? Staged burglary to obtain the insurance? Revenge assault? Sexual gratification? Where addresses three issues-- where did the crime take place? Where did objects of interest at the scene come from? And where else could they have been? Where did the crime take place is not as obvious as it may seem. The body of a young man is found in a shallow grave in a wooded area beside a public park.

Skip to 8 minutes and 33 secondsHe has been shot in the head, and the gun is underneath the body. Is this a murder that took place in the woods? Or was he killed somewhere else and the body disposed of in the woods to conceal the true locus? The same situation illustrates where did the objects of interest, the body and the gun, come from? And where else could they have been? We now are presented with a difficult reconstruction-- identifying the locus of the murder and the removal of the body. This example is a real case, and the investigation resulted in the identification of two linked scenes with the primary scene, where the murder took place, not being the initial scene, where the body was found.

Skip to 9 minutes and 19 secondsHow is about the modus operandi, or the method by which the crime was committed. A man calls the police and ambulance. His wife was cleaning the bathroom of their fourth floor apartment and has fallen from the window. The deceased is wearing a sweat top and trousers, one untied sneaker, and yellow cleaning gloves. Examination of the bathroom shows the safety catch on the window is released. The bathroom is clean and tidy, except for the second sneaker on the floor by the window. The husband offers the explanation that she must've opened the window to clean it, but lost her footing because her sneaker laces were not tied, and fell to her death.

Skip to 10 minutes and 2 secondsWhen the body was undressed in preparation for the post mortem examination, blood was found on the right hand and inside the right glove. The bathroom was examined again using sensitive tests for blood, and showed widespread staining with what was identified as the wife's blood. This turned out to be a case of murder with the modus operandi intended to make it look like an accident.

Skip to 10 minutes and 30 secondsWho arises in several situations. Human identity is central to criminal investigation. Victim, perpetrator, and witnesses all must be identified. Objective answers can come from the plethora of techniques used to establish personal identity, ranging from DNA and fingerprints through facial recognition to tattoos and personal possessions. The techniques used will depend on what is available. The body in the woods example was solved because a police officer recognised the face of the deceased and a bulletin released by the investigators. In general, the reliability of personal identification is best when it is based on immutable characteristics intrinsic to the person, DNA and fingerprints, and diminishes as we progress through characteristics that change or can be changed.

Skip to 11 minutes and 23 secondsTattoos, surgical implants, and with distance from the body, personal possessions. However, establishing personal identity depends on the context. Approximately 1,000 people were killed in Haiti in the 2008 hurricane season. Haiti is an incredibly poor country and resources like DNA testing and dental records were not available. Many of the dead were identified by relatives who recognised the clothing that they were wearing, even though the bodies were too decayed for facial recognition. The image shows, clockwise from top left, a stylised representation of a DNA helix, the heavily tattooed torso of a man, and an x-ray of a broken collar bone fixed with a plate and screws.

Skip to 12 minutes and 12 secondsAn x-ray of the healed injury itself could provide information to identify the person, and this would be even stronger if the plate and screws were left in position. When and why. When deals not only with the absolute timing of something, but also the sequence of occurrence. Two of the most important examples of when are estimation of time of death in the investigation of suspicious deaths, and estimation of post-coital interval in investigation of rapes. Absolute is somewhat misleading here, since both examples can only produce an estimated range of the time. The time of a recent death, within 48 hours or so, can be estimated from body temperature and the progress of rigour mortis.

Skip to 13 minutes and 3 secondsThe time of death in older remains can sometimes be estimated from the progression of infestation with maggots. The photograph shows flies feasting on a dead fish head, where some will lay eggs. Post-coital interval can be estimated from the amount of sperm recovered from vaginal swab. Why, in the sense of motive, can seldom be answered from real evidence. But it is a valuable question in reconstructions by continually posing questions such as, why does this look that way? Why is that missing or in an unexpected place? The examples given illustrate the values of the six W's in reconstruction, not only in their own right, but also in the way that they interact to recreate events.

Skip to 13 minutes and 52 secondsThinking about events in the How example resulted in a revision of what had happened, and having arrived at the conclusion of murder staged to look like an accident, the question of who was also answered. The answers to the questions where and who in the body in the woods case eventually also answered the question, what? It was not a murder, but a suicide in which associates of the deceased had attempted to conceal the death because they and the deceased were illegal immigrants. The crime scene is not only where the forensic science contribution to the investigation begins. It can also be where it ends. Perhaps for good reason.

Skip to 14 minutes and 33 secondsIt is clear that no crime was committed, or perhaps for not so good reasons, vital evidence was missed, degraded, or contaminated. Crime scene reconstruction can be a highly demanding and rewarding activity that mirrors the fundamental process of scientific discovery. The formulation of a hypothesis to explain observations, its testing and its possible revision, rejection, or acceptance. It is not always exciting. It can be incredibly boring and repetitive. For example, in the body in the woods case, more than 95% of the potential evidence collected by the scene examiners over several days of searching was never used. On the other hand, each scene is an unknown. It may be the same as the last one or completely different.

Skip to 15 minutes and 23 secondsBut the investigation of every scene must follow the principles of control, preserve, record, recover, and reconstruct. And above all else, the investigator must maintain an open mind and explore all reasonable explanations for what is found. The theory must be developed to fit the facts, not the other way around.

Roles and reconstruction

Wait - where did Roles come from? It isn’t in the CoPRRR mnemonic!

Quite correct, but we had to illustrate the potential complexities of scene examination, and how these are dealt with by application of a matrix of roles to overlay the investigative structure.

The central segment, on reconstruction, introduces us to the fictional character of Sherlock Holmes. Holmes is no more a reliable example of a forensic scientist than is the case with most of the popular current media representations, but the quotation shown here (and repeated later in the course) distils rather nicely what reconstruction is - or should be - about. We then take a step-by-step (or W-by-W) run through the 6Ws to see how they are used in reconstruction.

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This video is from the free online course:

Introduction to Forensic Science

University of Strathclyde