Expert Witness (16 page)

I then interpreted the results further based on what Mr Sheep said had happened on the night in question; that he was in the company of the perpetrator, that he had man-hugged the perpetrator when they first met, that they had sat next to each other in the velour-covered booth seats at the pub and that they had swapped seats. Having considered every thing I'd been told, I couldn't exclude the possibility that transfer of three fragments had taken place by way of secondary transfer.

In yet another, more sinister example, a burglar went on a spree on a chilly winter's night, breaking into a number of properties at an industrial site. At 2.15 a.m., PC One and PC Two attended the scene.

A few streets away, Mr Unlucky left his house at around 2 a.m. to go to work. Sometime later, he was struck on the head with a metal pole and his rucksack was stolen.

At about 5 a.m. a Mr Smith was subjected to what was called a stop-and-search, which was some thing the police could do if they had good reason to think the person was up to some thing suspicious or if they fitted the profile of a criminal seen in the area. The stop-and-search was conducted by PC Three, who was assisted by PC Two and PC One, both of them back on
patrol after having attended the earlier burglaries. PC One restrained Mr Smith by taking hold of his arms while PC Three conducted as thorough a search as possible given he was at the roadside. This involved a ‘pat-down' of his outer clothing and visible pockets, as it seems Mr Smith wasn't very cooperative.

At the time of the stop-and-search, Mr Smith was riding a mountain bike and carrying a rucksack. He told PC Three the rucksack didn't belong to him and he'd found it in the street. As the rucksack was essentially lost property, it was seized by PC Three, but he didn't look in it.

Mr Unlucky was found in the street by a pedestrian and, after receiving the call over his police radio, PC Three attended the scene. At about 5.30 a.m. he administered first aid to Mr Unlucky, including cardiopulmonary resuscitation (CPR) and he also searched through the injured man's clothing to try to find some form of identification. Mr Unlucky was taken to hospital, accompanied by PC Three. After Mr Unlucky died, PC Three took possession of Mr Unlucky's clothes and took them back to the police station.

Once it was known that glass might be an issue in the case, PC Three gave in his stab vest and work shirt at the end of his shift so they could be examined for glass fragments.

A hooded top belonging to Mr Smith was seized two days after the night of the burglaries and the attack on Mr Unlucky. Dozens of fragments of glass were recovered from the top. Five glass fragments were recovered from Mr Unlucky's clothes, which matched glass from Mr Smith's clothing. Samples of glass from the burgled premises were examined and matched glass that had been found on Mr Smith, Mr Unlucky and PC
Three. The police were suspicious that maybe Mr Smith had been involved in the burglaries and then the attack on Mr Unlucky. Initially, the fact that PC Three had attended to Mr Unlucky was unfortunate for the police, because it wasn't possible to tell whether PC Three had transferred the glass to Mr Unlucky (which would mean that Mr Smith might not have transferred glass to the deceased) or if PC Three acquired glass fragments from Mr Unlucky (putting Mr Smith back at the scene of the murder). The rucksack recovered from Mr Smith had belonged to Mr Unlucky. So had he really found it in the street or had he been Mr Unlucky's attacker?

The glass work in this case was quite complicated, so I'm not going to précis it. Take it from me that the critical issues were not only the number of glass fragments recovered from each individual but the physical and chemical properties of those glass fragments, as well as the order of events. Mr Smith was eventually found guilty of burglary and manslaughter.

Moving on from case examples to modern policing of crimes involving glass, police in England have developed a ‘crime scene kit' to give to bar and pub owners to collect glass samples after drunken brawls. Glassings or bottlings, when a glass or bottle is smashed before being thrust into the victim, often in the face, are a common occurrence in British society, usually after 10 pints of lager and shortly before a kebab on a Saturday night.

The biggest problem with cases of this type is that witnesses are often drunk and can't really remember what happened, the CCTV footage isn't always clear and the glass used in the
event is usually crushed and then swept up because, obviously, it's dangerous. In cases where broken glass is successfully recovered, the scientific results can be very good — fingerprints can demonstrate the manner in which a bottle was held (bearing in mind that the neck of the bottle is often the strongest part), DNA from blood can show whose body said weapon was used against but, too often, this type of information is lost in the aftermath.

Police in Plymouth, Devon, have decided to try to combat the problem of lost evidence by handing out clean dustpan and brush kits to local pub and bar owners so they can collect the ‘evidence' for later examination.

To me, this could go one way or the other. On the one hand, it's good because the collection of this sort of information could potentially increase the number of successful convictions in what is a horrendous and often life-altering event for the victim: in the short term, blood transfusions are often required for victims in order to replace lost blood; longer term, severe scarring is not uncommon. On the other hand, if these dustpan and brush kits are used by bar and pub owners, the chain of custody doesn't start with law enforcement personnel — it's an open book for criticism by the defence regarding the manner in which the glass was collected before it reached the hands of the police. A bar manager could choose to ‘fit someone up' because, let's face it, the chances are that they know the troublemakers. I think only time will tell with this one but I'd be interested to be involved with cases of this type as an independent expert, just to see how the prosecution laboratories and the police handle the evidence collection side of things.

During my time in England I had the dubious pleasure of being involved with many cases relating to drug traces on bank notes. Unlike those of us living in countries with polymer money, such as New Zealand or Australia, those who live in countries with paper money are carrying around bank notes practically all of which bear minute traces of cocaine. At my last look at the database of English bank notes that had been tested for drug traces, 70 per cent of them bore traces of MDMA (Ecstasy), five per cent bore traces of diamorphine (heroin) and five per cent bore traces of THC (found in cannabis). More than 99 per cent of them bore traces of cocaine. This doesn't necessarily mean that cocaine is the drug most widely used in England and Wales. It just means that, for some reason, traces of cocaine tend to be retained on bank notes more readily than other drugs. The exact mechanism for this is not fully understood but various tests have been undertaken and the bank notes themselves have been examined in various ways, including scanning electron microscopy in order to visualise the structure of bank note surfaces. And the reason analysis of individual bank notes is undertaken? Quite frankly, because they can. I should also add here that it's not just banknotes that are examined. Swabs are also routinely collected from vehicles, mobile phones, clothes and the surfaces of bags containing bank notes. Basically, anything that can be swabbed can and is examined for the presence of drug traces.

Banknotes are seized in a variety of cases including criminal cases, Customs and Excise and under the Proceeds of Crime Act. Before this technology came along, in drug-related cases, particularly dealing and trafficking, large quantities of bank-
notes were either swabbed en masse or were vacuumed in order to collect any drug traces present. The current method means bank notes can be analysed one by one, which means that if one bank note is very contaminated, it can be picked out.

There are now answers to some previously difficult questions, such as how do you know it wasn't just one heavily contaminated bank note that contaminated all the rest? Or, the outer bank notes were handled by Drug Squad officers so they must have contaminated them and that's what's caused the results. Some nice people at the laboratory will analyse a selection of individual bank notes in a non-destructive manner. Some times, those nice people at the laboratory will travel to court to give evidence about what they found. Some times, someone like me might go along as well to add comment for the defence. It's been a hard-fought battle to get this method of analysis accepted in court, partly because people like me flogged away at the inadequacies until it reached the stage it's at now. I personally have no problem with the methods, analysis or even the interpretation — as long as it relates only to English sterling bank notes; to my knowledge, there is no adequate database for interpretation of other currencies (except perhaps euros). In my humble opinion, very careful consideration should also be given to databases regarding drug traces in vehicles, on mobile phones and many other items.

In order to be able to under stand the sensitivity of the technique that detects tiny drug traces on items like mobile phones, money, clothing and cars, we need to under stand the size of the particles that can be detected. The method can detect nanogram weights of drugs. That's 10 to the minus 9 or 0.000000001 gram. To try to under stand the size of this, if
a single grain of salt were taken and divided into a thousand parts and each of these individual parts were then subdivided again into a thousand parts, one of those final parts would represent the approximate level of sensitivity of the analytical device. Alternatively, if the total amount of drug traces present on one million sterling bank notes (each contaminated at nanograms levels) were bulked together it would amount in size to no more than a single grain of salt. The quantities of drugs potentially detected by this technique are such that the drugs would not be visible with the naked eye.

You have to be careful with this kind of scientific information, though, because it sounds extremely impressive. It's like DNA — once a DNA result has been presented in court, it is extremely hard to cast any measure of doubt on the result, even if it were fundamentally flawed in a given case; it's just a function of the automatic weight that triers of fact place on DNA findings. It's similar with drug traces on items; people are fascinated to hear about the prevalence of these drug traces and it creates an automatic acceptance of the results. In more than one case, though, the defendant's money was found to be contaminated with one drug but he was charged with supply of a different drug altogether. In one case, the problem the police had was that despite a small amount of cannabis found on the defendant at the time of his arrest, there was no bulk quantity of any other drug recovered. He admitted to being a cannabis user but denied supply. The police prosecuted him because high levels of drug traces were found on his money but no one on the Crown's team looked to see that the charge related to cannabis while the money suggested heroin. Who knows where the money came from, but even the police didn't
think he was a heroin dealer. The case was chucked out of court. Lesson from this case: take a good look at your whole case, including the scientific results, before bringing charges.