From The (London) Telegraph
By Sarah Knapton, Science Correspondent
Fingerprint evidence linking criminals to crime scenes has played a fundamental role in convictions in Britain since the first forensic laboratory was set up in Scotland Yard in 1901.
But the basic assumption that everyone has a unique fingerprint from which they can be quickly identified through a computer database is flawed, an expert has claimed.
Mike Silverman, who introduced the first automated fingerprint detection system to the Metropolitan Police, claims that human error, partial prints and false positives mean that fingerprints evidence is not as reliable as is widely believed.
Nobody has yet proved that fingerprints are unique and families can share elements of the same pattern.
And there are other problems, such as scanning fingerprints of the elderly as their skin loses elasticity and in rare conditions leaves some people with smooth, featureless fingertips.
Mr Silverman, who was the Home Office’s first Forensic Science Regulator, said: “Essentially you can’t prove that no two fingerprints are the same. It’s improbable, but so is winning the lottery, and people do that every week.
“No two fingerprints are ever exactly alike in every detail, even two impressions recorded immediately after each other from the same finger.
“It requires an expert examiner to determine whether a print taken from crime scene and one taken from a subject are likely to have originated from the same finger.”
However there are numerous cases in which innocent people have been wrongly singled out by means of fingerprint evidence.
In 2004, Brandon Mayfield, was wrongly linked to the Madrid train bombings by FBI fingerprint experts in the United States.
Shirley McKie, a Scottish police officer, was wrongly accused of having been at a murder scene in 1997 after a print supposedly matching hers was found near the body.
“What both cases clearly demonstrate is that, despite the way fingerprint evidence is portrayed in the media, all comparisons ultimately involve some human element and, as a result, they are vulnerable to human error,” said Mr Silverman who has recently published his memoirs ‘Written in Blood’ and now works as a private forensic consultant.
“And the fingerprint often isn’t perfect, particularly at a crime scene. It might be dirty or smudged. There are all sorts of things that reduce the accuracy.
“I think it is important that juries are aware of this. Too often they see programmes like CSI and that raises their expectations. What you see on CSI or Silent Witness simply doesn’t exist.”
Unlike other forensic fields, such as DNA analysis, which give a statistical probability of a match, fingerprint examiners traditionally testify that the evidence constitutes either a 100 per cent certain match or a 100 per cent exclusion.
Previous studies have shown that that experts do not always make the same judgment on whether a print matches a mark at a crime scene, when presented with the same evidence twice.
A study by Southampton University found that two thirds of experts, who were unknowingly given the same sets of prints twice, came to a different conclusion on the second occasion.
It was Scottish surgeon Dr Henry Faulds who first discovered that fingerprints might be useful for identification purposes. He published a paper in the journal Nature in 1880 and offered the idea to the Met Police, but at the time the force was not interested.
Undeterred, Dr Faulds approached Charles Darwin who passed the concept on to his cousin Francis Galton. Galton published a book on the forensic science of fingerprints and claimed that the chance of two people having the same prints was about one in 64 million.
On the back of his work and later research Fingerprint Bureau was founded at Scotland Yard in 1901 and eventually the national Forensic Science Service (FSS) was founded with provided services to all UK forces.
However in 2010, the service was closed and forensic work is now carried out by the private sector, although the Met Police recently re-established its own lab.
Mr Silverman, whose opinion was sought on the murder cases of Damilola Taylor and Rachel Nickel, believes the closure of the FSS could lead to miscarriages of justice in the future.
“Police forces have to slash their budgets and the easy thing not to spend money on is forensic services,” he said.
“You have to ask yourself what price you put on justice.”