Crime scene examinations -
joining up the dots (August 2005)

Forensic Access underlines the importance of crime scene evidence in defence team thinking

• the importance of visiting the scene of the crime; what to ask for

• tips for instructing defence scene examiners

The natural and logical starting point in the investigation of a crime is at the scene - where it all happened. The scene might not necessarily be a single location. A body killed in one place and dumped in another for example immediately provides two loci and the route between them and mode of conveyance yet two more at least. Whether single or multiple, relatively simple or complex, scenes of alleged crime are rich sources of information about who did what to whom, when and by what means; they can provide the essential contextual background against which much scientific evidence needs to be seen. The scene should feature prominently in defence team thinking, just as it does in the mind of the primary investigators.

Blood stains for example may be interesting enough by their very presence but, often their physical appearance has much to tell about the way in which they were formed. There are ‘contact’ stains, ‘impressions’, ‘smears’, ‘impact spatter’, ‘secondary spatter’, ‘cast-off’, ‘arterial spurting’, ‘spray from coughing following congestion of blood in the mouth or airway’, and other sorts. It’s only by thoughtful, careful, competent examination and interpretation of blood stains, the patterns they form and, importantly, where they are in relation to others and other things, that their proper significance can be deduced. The finding of what could have been interpreted as ‘impact spatter’, low down on a piece of furniture might have led to the conclusion that there was an attack site, also low down, adjacent to it. But the scientist engaged by the defence was able to take into account the presence and significance of a pool of blood on the carpet there. What we were in fact dealing with was not an attack site, but ‘secondary spatter’ resulting from blood continuing to drip passively in the same place. In this case it was crucial to look at the surroundings as well as the blood pattern itself.

It has long been recognised that information about a crime tends to decay rapidly with time and that there is a need to crack on with the investigation before evidence is lost. In terms of scene examinations, scientists acting for the defence are inevitably at a disadvantage because they come along later, often much later, after the primary work has been done. They rely heavily on records made at the time and have to take on trust that these are sufficiently full and complete to enable fresh interpretations to be made. But scenes are sometimes preserved, enabling defence scientists to make their own observations notwithstanding the legitimate disturbance and removal of items that will have already occurred.

It was several months after she had been killed that a woman’s body was found hidden in a cupboard at the house she shared with her daughter. It was even longer before the scientist retained by the defence could have a second look and assess things in the light of the daughter’s account in which she spoke of having ‘lost it’, hitting the wall with a hammer before striking the single, fatal blow. But an examination of the dead woman’s clothing had revealed what could have been knife cuts in her cardigan and these cast a long shadow over the daughter’s role.

In the cupboard the remains of insects abounded and the fact that the cupboard door did not form a good seal, allowing insects to infest the body, became evident to the defence team for the first time. With this finding, the focus of the defence examination returned to the ‘knife cuts’ in the cardigan. Could this damage have had anything to do with insects? Their fresh and detailed scrutiny led to the conclusion, which was accepted, that they could; indeed, it was agreed that they were not cuts at all but tracks in the knitting left by feeding larvae. The hammer blow to the wall was also located and all of these things helped the court decide to accept a plea to manslaughter on the grounds of diminished responsibility.

In another case, a man was said to have set about his friend with a hammer. The defendant denied the attack saying that the two of them had been drinking at home for some time, after which his friend had fallen down some steps in the hallway. He had picked himself up and made it outside. Received information was that there were blood spots all over the flat, and pools of blood in the street outside where the injured man collapsed after his supposed ordeal.

Although several weeks had passed since the alleged incident, examination of the scene on behalf of the defence proved to be crucial. It had transpired that the defendant suffered from a medical condition resulting in so-called ‘projectile vomiting’. This meant that he was given to spattering his surroundings with small amounts of projected vomit and blood, some of the latter forming discrete spots on the surfaces on which it landed. Clearly, such spots had nothing to do with an attack. There was however an area containing a pattern of small blood spots in the vicinity of the hall steps where the man said his friend fell; there were no blood spots at all where the friend said he was attacked, nor any between there and the street. Armed with this information, the defence team successfully made their submission that there was no case to answer.

While these two cases clearly illustrate the value of scene examinations carried out on behalf of the defence, even long after the event, they also highlight the quintessential importance of understanding the context in which scientific evidence is derived.

There is increasing reliance on DNA profiling in crime detection and the prosecution of offenders. But the very power of current DNA technology and the mind-boggling statistics that come from it makes it all the more important that context is fully understood. The man whose semen (according to DNA profiling and massive numbers) was found on a sheet from the bed on which he was alleged to have raped the occupant of the house has reason to appreciate this. It was apparent that the staining at issue did not comprise smudges and smears as might have been assumed; rather, it was the result of a drying pool of semen. Even the nature of the content of the stain had been altered as the liquid semen had progressively migrated (soaked) though and dried on the cloth. These observations prompted further enquiries and it transpired that the man had legitimately stayed at the house for a number of weeks and that the bed sheet had come from the bed he had been occupying. The case, largely reliant on apparently overwhelming DNA evidence, fell away.

A seemingly unassailable combination of fingerprint and DNA evidence from a dribble of the victim’s blood provided a powerful link between victim and alleged assailant. Crucially, the two sorts of evidence had been found on a serviette apparently discarded where a girl had been brutally assaulted in a room in a block of flats. As evidenced by a trail of blood, she had managed to escape from the room and make her way downstairs and to the street. The defendant was a habitual visitor to the flats; he and others would fetch take-away meals, presented in or with serviettes, and consume them at a friend’s flat in the same block. Close scrutiny of the scene records showed that the serviette had not come from the room in which the attack took place, as had been assumed, but from the communal stair well, frequented by the defendant in the normal course and down which the victim had left a trail of blood on her way to the street below.

Arrangements can be made for scientists acting for the defence to visit scenes of crime and clear advantages can accrue if they are called out as early as possible, hard on the heels of the scientist who has been used by the police. Scenes involving bloodstaining can have a particular tendency to reward early scrutiny since, by definition, they tend to deteriorate, but in practice the problem of loss of information usually goes deeper than that.

Police photographers will normally have taken a multitude of shots, often from every conceivable angle, but these will not necessarily show precisely what the defence will want to see. A problem for the defence is that the available visual records - there can be plans too - tend not to be disclosed until later on. This can make life difficult in the effort to fathom what was done at the start and in attempting to ‘join up the dots’.

Items and samples are legitimately taken away from a scene, rendering its original state progressively more obscure. What is worse is that by the time the defence team are in a position to consider the scene in the light of all the other information, it will often have been ‘let go’ by the police and handed back to the ‘owner’. In these circumstances it might become difficult to resist acceptance, as fact, of what is being said about the scene by experts who have enjoyed the privilege of seeing it in its virgin state. The defence teams are then palpably not on equal terms.

It is preferable to see the scene first hand, crucially in order to be in a position to ask meaningful and penetrating questions about the observations already made and tests carried out and from which conclusions have been drawn. In short, the need is to appreciate the complete picture to get to the heart of the important issues.

Scene examinations for the defence can be pivotal in identifying additional enquiries that need to be made and further work to be done. Along with careful scrutiny of all available records, scene examinations better enable the provenance of key evidential material to be verified and for issues of continuity and contamination to be properly addressed. But defence teams face a fundamental problem concerning whom to instruct and how to secure sufficient funding.

Scene examination and interpretation cannot be learned from a book. Enquiries of potential scene examiners need to be made as to what experience, and in what role, the person has. Has he or she a proven track record in, for example, blood pattern analysis? Although there is still a long way to go, the forensic science profession is slowly becoming more regulated and more transparently qualified. The Council for the Registration of Forensic Practitioners (CRFP), which was set up in response to pressure from within the profession itself, continues to play a key role in this and increasing numbers of forensic scientists are being scrutinised by the CRFP and, if they pass muster, formally accredited by it. One is entitled to enquire of a scientist who is not accredited, “Why not?” There might be a very good reason but, equally, it might be because they are not up to the job.

As to funding, this is an ever-present difficulty and the bean counters still pretend that cheapest is best. It’s patently not and there are already too many examples of self-appointed, shoe-string experts whose advice has been unhelpful at best and positively misleading at worst. A way round the costs issue can be for defence teams first to establish the credentials of the scientist it wants to instruct and then to discuss with them how their instructions can be focused only on what is pertinent. By unequivocally establishing competence and relevance, better and more persuasive cases for funding can be made. Often working against this is the reluctance of some lawyers to admit that they are somewhat bemused by the forensic science evidence confronting them and how best to deal with it. There is no need to be reticent; a reputable practice will be very ready to help sort things out and to propose programmes of work, including scene examinations, that are meaningful and ensure value for money for the public purse.

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