Lawrence LeBlond for redOrbit.com – Your Universe Online
Forensic detectives have been relying on unique fingerprints to catch criminals for more than a century, but a new report by the Home Office’s first Forensic Science Regulator said human fingerprints may not be as unique as once thought.
Mike Silverman, the man who introduced the first automated fingerprint detection system to the Metropolitan Police, claims that this foundation of forensic investigation and identification is flawed, noting that human error, partial prints and false positives is making fingerprinting less reliable as solid evidence in whodunit cases.
“No two fingerprints are ever exactly alike in every detail; even two impressions recorded immediately after each other from the same finger,” said Silverman. “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.”
“And not everyone’s fingerprints have been recorded so it’s impossible to prove that no two are the same,” he added. “It’s improbable, but so is winning the lottery, and people do that every week.”
Silverman said that there are other factors that also reduce the ‘uniqueness’ of fingerprints, such as some skin conditions, which can make fingertips smooth. As well, elderly citizen’s skin changes in elasticity, making their prints seem warped. Furthermore, families are also known to share similar patterns.
Silverman stressed that, because of these printing inconsistencies, it is important that juries are made aware that not all fingerprints are unique.
“Too often they see programmes like CSI and that raises their expectations. What you see on CSI or Silent Witness simply doesn’t exist,” Silverman said, as cited by Mail Online’s Sian Boyle.
“[In reality] 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,” Silverman told The Telegraph’s Sarah Knapton.
Criminal investigations have led to numerous cases in which innocent people have been wrongly accused based on inaccurate fingerprinting evidence.
One such case occurred in 2004, when Brandon Mayfield was wrongly linked to the Madrid train bombings by US federal fingerprint experts. Another case involved Scottish police officer Shirley McKie, who 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 Silverman, who now works as a private forensic consultant.
Unlike DNA analysis, which gives a statistical probability of a match, fingerprint experts rely on evidence that constitutes either a 100 percent certain match or a 100 percent certain exclusion.
The problem is that not all experts make the same judgment on whether a print matches a mark at a crime scene when presented with the same evidence twice.
A recent study by Southampton University found that two thirds of experts who were unknowingly shown the same sets of fingerprints twice came to a different conclusion on the second occasion.
Fingerprinting technology was first used in Scotland Yard in 1901, after an earlier study by Dr Henry Faulds discovered that they may be useful in identifying individuals. That paper, published in the journal Nature in 1880, did not interest the Met Police at the time, wrote The Telegraph’s Knapton.
Dr Faulds remained undeterred. He approached Charles Darwin with the idea, who passed it along to his cousin Frances Galton, who published a book on the forensic science of fingerprints, claiming that the odds of two persons having the same prints was about one in 64 million.
On the basis of this book and later research, the Fingerprint Bureau was founded in 1901 and eventually expanded out to the creation of the Forensic Science Service (FSS), which provided services to all UK police departments.
The FSS remained in service until 2010, when the private sector took over all forensic work. The Met Police recently re-established its own forensics lab.
Silverman, who worked with police on the murder cases of Damilola Taylor and Rachel Nickel, believes the closing of the FSS could lead to future miscarriages in the justice system.
“Police forces have to slash their budgets and the easy thing not to spend money on is forensic services,” he told Knapton. “You have to ask yourself what price you put on justice.”