CSI – Crime Scene Indeterminacy

6 May

With the advent of DNA profiling, many people assumed that the age-old problem of identifying and convicting criminals would become pretty much cut and dried.

This cheerful belief has been reinforced by most of the TV programmes that feature forensic scientists and pathologists as their central characters.

Unfortunately real life doesn’t quite work that way.

It’s worth noting that anyone who actually works in a crime lab would amongst the first to tell you this. (Generally speaking, scientists are keenly aware of the limitations of their techniques and their equipment and they’re often quite candid about them if anyone ever bothers to listen to them).

Incidentally, you can always tell when a politician has absolutely no grounding in science and very little understanding of technology because they always have boundless faith that complex problems can be quickly and easily solved by new technology. They also invariably assume that this technology will infallibly work first time and every time. (Anyone who pays attention to current affairs will doubtless be able to call to mind various examples of ambitious and generally hideously expensive high-tech projects that eventually came to nothing and had to be cancelled).

Of course in TV crime shows the story almost always ends in the criminal being unmasked and their guilt proved as the ineluctable consequence of systematic investigation and deduction.

Well, okay, it makes for a good story and I’m not knocking it. I like a good story as much as anyone.

But you have to take these TV shows with a pinch of salt and not get carried away with the notion that criminal investigations are always going to end with such a conclusive result.

In the first place most TV crime labs are packed with all the latest equipment and it’s all nice and shiny and works perfectly every time. (One suspects that real life forensic scientists might watch such programmes in the much the same spirit that people on the minimum wage might have watched Lifestyles of the Rich and Famous).

A second point to bear in mind is that the scriptwriters are on the side of the investigators. They can be remarkably ingenious in the way they will drop in rare genetic disorders, unusual types of pollen or whatever else they might need in order to provide neat, conclusive results that will determine guilt or innocence with absolute certainty.

I’m not knocking it because as I said; it makes for a good story and I like a good story as much as anyone.

Having said that, there is a risk that the general public and worse still politicians and journalists, who can be quite painfully ignorant of science (and just about everything else), will tend to overestimate the ability of modern police methods in ‘proving’ a suspect’s guilt.

The reason all this comes to mind is not because I have any kind of background in Law Enforcement, nor is it because I’ve recently been involved in any kind of criminal investigation. It’s simply because I’ve been cited for jury duty. 

Again. (Actually I don’t mind too much, it’ll be a break from my painfully low paid and frequently exasperating job).

Obviously there’s no way of knowing whether or not I’ll be selected or, if so, what kind of case I might be sitting on, but it does call to mind my previous experience of jury duty.

Obviously I can’t reveal any details of the jury’s deliberations and I don’t intend to say too much about the specifics of the case, but it was an educational experience and I’d like to offer a few observations in case they might be instructive to someone else.

One of the quirks of Scottish criminal court procedure is that there are no opening statements.

Once the preliminaries are over, the prosecution simply starts presenting evidence. This can be a little disconcerting for a juror in as much as you’re hearing evidence with only the text of the charge to give you any idea of what the whole thing’s about. This can make it hard to decide what’s important and what’s incidental.

The case I was sitting on was a murder. The victim and the defendant had been a couple; both with a history of multiple addictions and both of whom had been in and out of prison for most of their adult lives.

They were living in a block of flats that you would only move into if the alternative was sleeping rough.

One of the witnesses was a rarity in this community in that he had a job. It was his habit not only to lock his door when he came home for the evening, but also to barricade it with old car tyres in case someone tried to force it. His evidence was limited because he kept himself to himself and when he heard a disturbance that later turned out to be the murder being carried out, he simply kept his head down and hurried away.

I’m not inclined to judge him for this.

He was having to survive in an environment where altercations would have been frequent and where he couldn’t knock on a neighbour’s door with any confidence about what would happen if, and when, the door opened.

So we had a victim and we had a suspect.

We also had evidence from the police who attended the scene. People vary, as we all know, and police officers vary about as much as anyone else. Some of the police officers in this case gave very clear, credible evidence and you could have confidence in them. Others inspired a lot less confidence. Let’s leave it at that.

We also had lots of pictures to look at. Rather too many for some. (Not a jury secret. We had to have a break in the evidence because one of our number was becoming visibly distressed).

We also had our forensic evidence.

We had reports from the autopsy and we had some blood spatter and we even had some DNA evidence.

Without going into too much detail, it had always been perfectly obvious that the cause of death was essentially gross brutality on someone’s part.

Having said that, the pathologist’s evidence was quite surprising, because much of the earlier evidence we had been presented with had suggested that death was caused by a head injury, while the autopsy results showed that death was caused by internal damage as a result of severe trauma to the abdomen. The kind of trauma that might be caused if someone very heavy stamped on you.

In comparison, the head injury turned out to be relatively harmless.

So then we came to the blood spatter and the DNA evidence. This was the bit that one might assume was going to wrap the whole thing up one way or the other. It generally does in a TV show.

The blood spatter took the form of some very small spots of blood on the defendant’s clothes. DNA testing showed that the blood almost certainly came from the victim. This was expressed in terms of a probability of some millions (I forget how many) to one against the DNA belonging to anyone else.

The shape and size of the droplets indicated that they were the result of standing fairly close to some object soaked in the victim’s blood when it had been struck by something. (That was about as far as the expert witness was willing to go).

On the face of it that might seem to be pretty conclusive.

The blood almost certainly came from the victim and it had almost certainly travelled a relatively short distance (a few feet) as a result of a violent impact on something containing, or coated in, the victim’s blood. (The most likely candidate being the victim herself).

The simplest explanation for this evidence would be that the defendant had hit the victim.

On the other hand, it could have been that he had simply been standing next to her when someone else hit her. Or that she had been bleeding and some of her blood got onto a towel and she flicked it at him. (And no, I can’t think of any reason why anyone would do that). Or that he had hit her, but that didn’t necessarily prove that he had killed her. (The fatal injuries would have caused internal bleeding not blood spatter, therefore the defendant may well have hit the victim in the face, for instance, thereby causing the blood spatter, but that wouldn’t necessarily prove that he had killed her).

In other words, unlike the normal TV version, there wasn’t just one possible explanation for all this scientific evidence.

 And as a result, the scientific evidence wasn’t enough on its own to secure a conviction. We needed more in order to be sure, beyond reasonable doubt, that the defendant was guilty.

As a matter of fact, there was more evidence. Much of it circumstantial, it has to be said, but when it was all taken together we did reach a verdict. We found the defendant guilty. (In Scots law at present no single piece of evidence is enough to convict anyone. The prosecution has to have some kind of corroborative evidence as well).

I wouldn’t say that I have any doubts about the verdict we gave. I think we got it right, but the main thing I took from this experience was that the evidence needed a lot more interpretation than I had expected. If you’re tempted to think that juries are in danger of becoming redundant as forensic science advances, then I think you should probably sit in on a real trial in order to get a different perspective from the one presented on TV.

TV crime shows are not documentaries, they’re just entertainment. 

There’s nothing wrong with that, but if you think carefully about the details of the plotlines in your favourite crime show, you’ll probably see that a lot of time and trouble goes into setting things up so that the evidence tells a straightforward story. (Albeit after the requisite number of red herrings, and plot twists).

After we had given our verdict, the Depute Advocate General (prosecuting) read out some of the edited highlights of the defendant’s previous convictions and sentences. What struck me about this was that this was a man who had done the same (often violent) things over and over again, been caught, convicted and sentenced over and over again, serving a year here, eighteen months there, maybe as much as two or three years.

He had never killed anyone before, but when a twenty stone man stamps on a seven stone woman, the results are liable to be fatal even if that’s not his specific intention.

(In Scots law a killing can be murder if it’s the result of ‘wicked recklessness’, even if there’s no deliberate intention to kill).

So all in all, this wasn’t the kind of murder that’s likely to feature on CSI Miami, for example. There was no glamour, no plot twists or bizarre details, just a whole load of misery and pain and ultimately a sickening waste of life.

You could say that the victim in this crime didn’t have much going for her. Whatever talent she might have had seemed to be swallowed up in booze and smack and so maybe you could say that she’d missed or blown whatever chances she’d had in life. She certainly made a poor choice of partner.

On the other hand, maybe it’s better to point out that whatever else anyone might want to say about the victim, she had a friend and a mother who loved her while she lived and mourned her when she died.

Their pain at her loss was obvious.

That has to mean that her life had some value and some meaning.

Maybe that’s why Buddha said that we should have compassion for all living things. For all things that suffer.


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