'Go slowly. See all. And accept you might not be able to offer a complete explanation'

News item | 30-04-2024 | 10:08

You were part of the team that drew up a Dutch BPA standard. What struck you?

‘There are clear differences between the system in the UK and the Dutch system. I feel the NRGD is a really forward-thinking platform whereby we can ensure that people recognize and implement quality without hitting them with the stick of regulation. I think that it's a really good way in which people can recognize their own approach to a particular discipline. It makes them responsible for ensuring they're operating in a quality driven way. As to the NRGD itself, I think the register as a whole is a beacon in forensic science. I hope that the UK Forensic Science Regulator will continue to follow programs like the NRGD and try and assimilate some of what the NRGD does into the accreditation frameworks we have in Britain.

Secondly, I believe that the NRGD can help forensic experts to deal with expectations about what they can deliver. Strengths and limitations. When I'm delivering training, I have a number of quotes that I've collected as examples to demonstrate the pressure that can be put on someone when they go to a crime scene. Such as a crime scene manager who welcomes the scientist by saying: ‘I'm so glad to see you. We need some good news.’ And they haven't even gone through the door yet! ‘In comes ‘The Oracle’’. That kind of pressure. There are always going to be bits of information that you can robustly and reliably recover. But I think we need to be honest with ourselves and say, even if you've had this training, there is an element of ‘I don't know’ at the end of it. We need to recognise that.’

BPA scientists are not clairvoyants. In essence, BPA is very straightforward. The only tool you need as a BPA scientist is a good pair of eyes. If you can make observations about bloodstains, then you're on your way to becoming a BPA scientist. But I do think you need to have the ability to not jump to conclusions. You have to plan and slowly, gradually, plot your way through bloodstains, using observations and measurements, forming an idea of their distribution before you give your answer. And that answer could be: ‘I don't know’. But go slowly. See all. And accept that you might not be able to tell what happened.’

Does your job as a BPA expert require that you always visit the crime scene?

‘Not always. I do a lot of case reviews. And because of that, I'm usually working from the original case records. So that would include photographs, videos or notes. But that means that I’m already on the back foot. I start working from a position where I might not have enough information, looking at photographed bloodstains through somebody else's eyes. That someone only took the photograph because he or she felt that that was the way to do it. I’m not physically there at a crime scene, but just literally looking at a representation of what was there, and what somebody else felt was relevant or important enough to capture.’ We must recognise the legacy that BPA can have. This means that someone could be reviewing our case records years down the line – and so we need to make sure that we have captured everything in a way that allows others to inspect the detail of the bloodstains that were present and that our records are fit for purpose.’

Has that led to feedback to the police about their way of building up a dossier?

‘We do give feedback. I can think of 2 or 3 reports in the last few months where I've written words to the effect of saying: ‘If you had recovered this or recorded that in more detail, it would have been possible to tell you more about it.’ In the UK, we have crime scene teams that do the crime scene analysis and then we have people in the laboratory who do the DNA testing and the case evaluation, and there's a real disconnect there. Crime scene investigators are not considered to be BPA scientists. And so, when they're trained to do crime scene work, BPA is not necessarily part of their training journey. Unless a police force adds that on because they see the value in that skill, CSIs may have very little BPA knowledge. My job is to say to police forces: ‘If your people had BPA in their back pocket, they would be much better prepared to deal with blood scenes, and they would use that knowledge to not only sample the right stains the right way, but they would also recognise what the blood is telling them within that space.’ And ultimately, the way to sell that idea is to say that it will save money.’ With a BPA sampling strategy, crime scene investigators would have less samples for DNA analysis because they'll be immediately selecting the right stains, ones that reflect the different patterns. DNA is a really important intelligence tool, but it doesn't tell you how or why things happened. But the question of what happened is probably the most important question in crime investigation. So I think that any work that highlights the value that BPA can bring to a criminal investigation is good.’

Should the NRGD promote BPA?

‘I think that everybody wants to achieve better. I engage with police forces introducing them to bloodstain pattern training at an introductory level. The NRGD might very well do the same. And I think that would connect with the budget holders and make them understand that, with BPA on board, they can not only save money in DNA testing, but they can also get much more value from their investigations and ultimately put more perpetrators in jail. In my experience they react really well to that. Ultimately justice needs to be done. And importantly, BPA can help ensure that people are not subject to a miscarriage of justice.

Suppose you're a crime scene investigator with a basic knowledge about a broad range of crime scene techniques. At least you see that there are insects in a body, or that there's a footwear mark in a material. Your observations enable you to say: ‘Hang on a minute. We need to raise that up a little bit and get in an expert.’ If someone goes into a blood scene without an understanding of BPA, how can we expect those individuals to see BPA and use it in the way that we hope that they could use it? I think education and exposure are part and parcel of agencies and of individuals working in crime scene investigation. It is their responsibility. And it might even be BPA first and DNA later, in the sense that if you focus on BPA initially, for instance, you can always take a DNA sample later. Whereas if you focus wholly on DNA, you risk losing or missing valuable BPA information that could help to build a scenario.’

Are there any emerging areas within BPA, things you’d like to know more about?

‘At the moment, the area of BPA is a really interesting place because we're looking at the application of machine learning in pattern recognition. We feed photos into an AI system and it comes out with a determination. But we need to feed the system with thousands upon thousands of patterns. We need to do it pretty relentlessly. But the number of people that engage with this kind of research is exceptionally low. People don't share enough of their material. I think they're scared of AI. But the early results from this work are really encouraging, although we need to validate the approach in a way that is robust and reliable. So far, AI is throwing out results that make you think: ‘Wow, that's not far off’. I believe there’s a lot of possible growth in AI and I certainly think it has a place in this business. But to validate that kind of research we really need people to share their data and patterns. Anyone delivering BPA training should seek out AI researchers and invite them to record the thousands of patterns that they are producing on their courses. To contribute to the data.’

Reaching out: is that something scientists should focus on more?

‘I believe we should. I've got nearly 30 years of working with bloodstain patterns. I feel it's my responsibility to share that experience, showing how BPA can help solve crimes. It shouldn't take 30 years to get to that point: we should be continually feeding our experiences back into practice, so people can develop. We need to ensure that we don't get to a point where there's a knowledge gap. If the NRGD decides to engage with police and investigators and advocate the value of BPA for crime scene investigation, I think that will have an impact on people’s mindsets and affect the conversation around BPA. Actually, the NRGD could work on two sides. On one side, it could help establish the scientific value of BPA to forensic investigators. On the other side, it could encourage scientists to realize the societal impacts that our science can have on putting the right people in jail.

Let me give you a chilling example of what BPA can do. I work for a charity called Inside Justice who investigate miscarriages of justice. They investigate cases on behalf of people who say that they've been wrongfully convicted of a crime they didn't commit. So two guys were in prison for murder in the UK. The basis of the case was bloodstain patterns in a room. After the attack, in which a man was stabbed to the throat, these two guys were seen on CCTV ‘fleeing’ the scene. So the crime scene investigators went to the property and at the door to that crime scene the bloodstain pattern scientist was asked ‘Can you go into that building and tell us what happened? It's a crime scene.’ So that individual went into that room and interpreted the patterns. There was no projected blood in that space, which you might have expected from the neck injury, but nevertheless they interpreted the patterns, and that was that. The case came to trial and the two guys were convicted of the murder. They said ‘We didn't do it’. So the case naturally went through to appeal and was reinvestigated.

Now, outside the property there were other bloodstains because the deceased had not been found in the house. He'd jumped out of a window and travelled down the street and around the corner where he collapsed and died. The bloodstain pattern scientist was not asked to look at any of the other bloodstains, on the street, or at the site where the victim had died, because they'd been told ‘this is the crime scene, inside the property’. When the bloodstains outside the property were examined, it turned out that there was another assault site, on the path close to where the victim had collapsed. And this established that although the fight had started in the room and the victim had sustained relatively minor bleeding injuries there, he had then jumped out of the window and travelled up the road. Camera technology showed that after leaving the property, the victim was followed by another man, who stabbed him, fatally, in the neck. At the time that this happened, the two guys that were in prison were captured on CCTV streets away. So at the retrial, it was established that there had been a second site of assault which hadn’t been examined by the bloodstain scientist. The initial investigation had suffered from tunnel vision. And the same CCTV footage that had been shown in the first trial to demonstrate that two men were ‘fleeing’ the scene after a murder, showed that in fact they had been streets away at the moment of the fatal attack.

So: the same evidence. The bloodstains didn't change at all. It's just the fact that the bias of the investigation had driven everybody to think: ‘This is where the victim was stabbed.’ It's just terrifying that even when we make the decision to engage with BPA, we restrict its use. The investigators effectively said: ‘Go in the room and tell us what happened, but don't bother looking at the rest.’ And that's probably a budgetary decision, money may have played a significant part. It usually does. But even when we engage with BPA, we're not always getting the full value from it. As a BPA expert you should demand to be shown the whole scene, not just as in this case, the room, but outside and the place where the victim collapsed. You need that context. We have to empower scientists who are working in a commercial environment to challenge that commercial environment and say: ‘I can't do the job you're asking me to do if you try and restrict me in that way. I need to see that stuff.’ To stand firm, to know your strengths and limitations and know when to challenge bias. But that can be really difficult when you're a junior scientist just starting out in a career. It's difficult to challenge the norm or challenge superiority, challenging people who perhaps have been doing this job for years. So we need to empower our people. In the long run, it will touch upon the integrity of what you're doing, but you have to avoid the risk of your approach being framed by another person’s bias. We're naturally encouraged to build a narrative. Everybody likes to tell a story. But what we have to remember is that we're telling a scientific story, and the science within that sort of story has to be robust, defendable and evidenced. The guys in the case I was talking about spent four years in prison for a crime they didn't commit. We have to acknowledge that BPA put them there. So we need to go slowly. See all. And insist that we are shown all there is to see.’