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The strange case of the 'time travel' murder


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  • Elders (Admins)

This is copied from the BBC website (http://www.bbc.co.uk/news/science-environment-26324244) where it was posted earlier today:

A woman's body is found in London. DNA turns up a hit, yet the suspect apparently died weeks before the alleged victim. Here, forensic scientist Dr Mike Silverman tells the story of one of the strangest cases of his career.

It was a real-life mystery that could have come straight from the pages of a modern-day detective novel.

A woman had been brutally murdered in London and biological material had been found under her fingernails, possibly indicating that she might have scratched her attacker just before she died.

A sample of the material was analysed and results compared with the National DNA database and quickly came back with a positive match.

The problem was, the "hit" identified a woman who had herself been murdered - a full three weeks before the death of her alleged "victim".

The killings had taken place in different areas of the capital and were being investigated by separate teams of detectives.

With no sign of a connection between the two women and nothing to suggest they had ever met, the most "likely" scenario was that the samples had been mixed-up or contaminated at the one obvious place that they had come together - the forensic laboratory. A complaint was made by the senior investigating officer.

It was 1997 and I was the national account manager for the Forensic Science Service at the time, so it was my responsibility to find out if a mistake had been made at the laboratory.

My first thought was that perhaps the second victim's fingernail clipping had been mislabelled and had actually come from the first victim all along. As soon as I started to look at the samples, I could see this wasn't the case.

The victim had painted her nails with a distinctive leopard skin pattern and the cuttings that had been taken bore the exact same pattern. There was no doubt that they were the correct ones.

I then checked through the laboratory records to see if there was any way the samples could have been accidentally mixed-up.

This too turned out to be a non-starter as the two sets of samples had never been out of the lab's exhibit store at the same time. In any event, several weeks had passed between the analysis of the first and second clippings and different members of staff had been involved.

Determined to get to the bottom of the mystery, I decided to look more closely at how the clippings themselves had come to be collected and discovered that both bodies had undergone an autopsy at the same mortuary, though they had arrived there several weeks apart.

Forensic autopsies - those carried out in the case of murder or suspicious death - are far more detailed and involved than standard, non-criminal autopsies. Among other examinations, blood and organ samples are collected for toxicological testing, stomach contents are collected and analysed and fingernails are scraped and clipped.

It was while I was examining the mortuary records that I came across a possible answer. It transpired that the body of the first murder victim had been kept in the freezer for several weeks while the police carried out their initial investigation.

It had been removed from the freezer to allow the pathologist to take additional nail clippings the day before the body of the second murder victim had arrived at the mortuary.

The following day, the same pair of scissors had been used to cut the nails of the second murder victim. Although the scissors had been cleaned between uses, I couldn't help but wonder whether sufficient genetic material had survived the cleaning process to transfer onto the second victim's nails and then produce a DNA profile in the subsequent analysis.

I had started my career in forensic science during the late 1970s and back then, the idea of being able to identify someone from a few tiny drops of blood seemed like something out of science fiction.

In those early days, we rarely wore protective clothing at crime scenes or worried about potential contamination because there was no method to analyse any biological material that was as small as the eye could see.

Today, everyone entering a crime scene has to don a new, clean paper over-suit and overshoes as well as gloves since DNA retrieval techniques are now so sensitive that simply lightly touching an object - such as a door knob or knife handle - can leave enough of a trace to carry out a successful DNA analysis.

In 1997, the time of the mystery murder, DNA profiling was only a few years old and, as I was about to discover, the technology was improving so quickly that previously unforeseen problems were beginning to occur.

I arranged for the nail scissors from the mortuary to be analysed and discovered not two but three separate DNA profiles were present. Further examination found DNA contamination on several other mortuary instruments but it was only ever going to present a problem when it came to fingernail scissors.

The autopsy knives, for example, were found to have traces of DNA of several different people on them, but because incisions were never sampled for DNA, cross contamination was not an issue.

I immediately sent out an urgent memo to all coroners, mortuaries and forensic pathologists in the country, highlighting the problem and suggesting that, in the future, all nail clippings should be taken with disposable scissors and that the scissors should then be placed in the evidence bag with the nail clippings to confirm they had only been used once. It's a system that remains in place to this day.

Modern DNA analysis is now so sensitive that contamination is a major issue, with the potential to send criminal investigations spiralling off in the wrong direction.

In Germany in 2007, traces of DNA belonging to an unknown female were found at the scene of the murder of a police officer.

When run through the German database, identical DNA was found to have been present at the scene of five other murders in Germany and France, along with several burglaries and car thefts. In total, the woman's DNA was found at 40 separate crime scenes.

The German authorities spent two years and thousands of hours searching for the culprit, only to discover that the DNA had in fact been present on the swabs the crime scene investigators had been using to collect their samples. The swabs had been accidentally contaminated by a woman working at the factory that produced them.

For years DNA has been seen as the ultimate crime-fighting weapon with successful convictions arising from ever smaller traces, but in many ways DNA analysis has become a victim of its own success.

Now that we have the ability to create a DNA profile from just a few human cells, traces can be found almost everywhere.

But as we are all depositing DNA everywhere we go, the significance of finding and analysing these traces will become increasingly open to interpretation unless there is sufficient DNA material present to eliminate the possibility of secondary contact or cross-contamination, or additional evidence supporting direct involvement in the crime.

Dr Mike Silverman is the author of Written In Blood, a history of forensic science.

Many cold cases are now being solved thanks to improvements in forensic science, but this article is a good reminder that the methods of collection of evidence can be as important as the laboratory techniques. It's scary to think that there could have been wrongful convictions in those cases.

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Libby

"Humans need fantasy to be human. To be the place where the falling angel meets the rising ape." Terry Pratchett

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This is copied from the BBC website (http://www.bbc.co.uk/news/science-environment-26324244) where it was posted earlier today: Many cold cases are now being solved thanks to improvement

I have no doubts there are many wrongful convictions, and many innocent people are in prisons and jails. It is good that forensic science has improved as much as it has.

DarleneSignaturePic1.jpg

"Time is too slow for those who wait; too swift for those who fear;

too long for  those who grieve; too short for those who rejoice.

But for those who love, time is eternity."

(Jane Fellowes)

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  • Elders (Admins)

I agree that it's good that forensic science is getting better, because it's a means of shining a light on the truth. It's effective in convicting the guilty and exonerating the innocent - both of which are of equal importance in a good judicial system.

It's sad, though, that there isn't an equally rigorous scientific method of testing the truth of witnesses. Certainly witnesses can be confused about what they saw - eye-witness evidence is notoriously flawed, as are polygraphs. But, as we know, some witnesses blatantly lie, and it's the innocents who suffer the consequences.

Libby

"Humans need fantasy to be human. To be the place where the falling angel meets the rising ape." Terry Pratchett

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Witnesses are very good at lying, especially if it will benefit them, speaking from recent experience with people standing before the judge and lying through their teeth.

Rarely do the courts seek the truth anymore. Each person has their own agenda, including the judges, and truth is the last thing that is pursued. Again, speaking from recent experience. In and out of court for a year, and not one time did anyone seek the truth, not even the defense attorney. Pitiful how the system has become, and so need so to fall. It no longer serves the people.

DarleneSignaturePic1.jpg

"Time is too slow for those who wait; too swift for those who fear;

too long for  those who grieve; too short for those who rejoice.

But for those who love, time is eternity."

(Jane Fellowes)

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  • Elders (Admins)

Wow. Just goes to show, one slip-up in protocol and the wrong person gets convicted

It must be challenging for cold-case detectives, because they can't just re-run the forensics, they also have to take into account how that forensic evidence was taken.

But I've just remembered a recent case in the UK where there was a major slip-up in protocol. A man, who had already been convicted of a sex murder, confessed to another, and actually led the police to where he'd dumped the woman's body. But the detective-in-charge didn't follow the precise protocol in reading him his rights, so it wasn't possible to proceed to a prosecution. On a practical level, that doesn't make much difference, because the murderer isn't likely to get out of prison, and everyone knows he killed that woman, but she and her family didn't get the justice they deserved, they didn't get to see that man stand accused of his crime in a court room, and hear the sentence imposed on him.

Witnesses are very good at lying, especially if it will benefit them, speaking from recent experience with people standing before the judge and lying through their teeth.

Rarely do the courts seek the truth anymore. Each person has their own agenda, including the judges, and truth is the last thing that is pursued. Again, speaking from recent experieInce. In and out of court for a year, and not one time did anyone seek the truth, not even the defense attorney. Pitiful how the system has become, and so need so to fall. It no longer serves the people.

I was thinking very specifically about your son's case. It should always be about the truth, and everyone, no matter their status, should be held to the same highest account in terms of telling the truth. Civilian witnesses can sometimes mis-remember or be confused, but those whose jobs (and salaries) require accurate and precise evidence and adherence to the law have no such excuse.

Libby

"Humans need fantasy to be human. To be the place where the falling angel meets the rising ape." Terry Pratchett

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