Forensic finger-pointing

We leave them everywhere.

In our homes, our workplaces and even when we eat food a unique record of our passing. But are fingerprints as infallible an identification as we have always been led to believe?

Britain's leading fingerprint expert says not. Allan Bayle, whose fingerprint evidence helped convict Libyan Abdel Basset Ali al-Megrahi of the 1988 Lockerbie bombing earlier this year, quit the Metropolitan Police in June after 25 years because of what he believes are a mounting number of unsafe convictions resulting from poor forensic evidence.

The last straw was a case involving a female police officer charged with murder in Scotland two years ago.

"Shirley McKie was stitched up on the evidence of one fingerprint," says Mr Bayle. "She was supposed to have left her mark at the murder scene but it wasn't her and she nearly went to prison."

So-called experts refused to believe there might be a mistake before Mr Bayle, 50, of Great North Way, Hendon, got involved. It cost him dear.

"I was marched in and threatened with disciplinary action by my superiors but they dropped it."

WPC McKie didn't go to prison but did quit the police and left Mr Bayle feeling more and more uncomfortable with his work in the force.

With his faith in the police fading, Mr Bayle, who pioneered fingerprint research during his time at the Yard, heard from the sister of a successful businessman imprisoned on the evidence of a single fingerprint on a jewellery box.

Bolton entrepreneur Alan McNamara was jailed for stealing £33,000 of goods from a house in Rochdale. Mr Bayle's instincts told him it was another profoundly unsafe conviction.

"I looked at it and realised there was no grain on the print. In fact, it was so spread out that it must have come from a flat surface like a vase," he recalls.

"I then found out what McNamara did and realised he sells hundreds of vases every year. The case seemed completely implausible."

McNamara's lawyers asked Scotland Yard if Mr Bayle could represent their client, whom he believed to be innocent, at an appeal. But his bosses blanched at the idea of a Met officer giving evidence against another force, even to save an innocent man from prison so he quit in disgust.

"I had had enough and said I would leave to represent him and that's what I did."

McNamara's appeal takes place later this year. Meanwhile, Mr Bayle has set up a consultancy to help other people convicted of offences on the flimsiest of forensic evidence. Mr Bayle says that although the Met is very good in its forensic work, other parts of the country have a lot to learn.

"Scene examiners are not writing their notes correctly and that is the biggest problem. If you are checking procedures are right then nothing can go wrong," he said.

Mr Bayle believes officers are sometimes not writing down where they take fingerprints and that important aspects such as the angle the print was made at and associated factors are not being taken into account.

"All reports should be the same and they are not at the moment. Some of them are diabolical. Some examination officers mix up or cannot remember where they left the mark and innocent people have been convicted on the strength of that."

Mr Bayle says one of the biggest problems with forensic evidence is that legal representatives do not query fingerprints and accept them as infallible.

This view was echoed by Franklin Sinclair, chairman of the Criminal Law Solicitors' Association: "We have been trained to accept it [fingerprint evidence] as gospel. We can only challenge it if the client challenges it first, so what generally happens in 99 per cent of cases is when the Crown produces the evidence, the client goes 'Okay, I'm guilty'.

"It is very rare that a defendant will say he or she was never there and we need them to do that before we can query fingerprints. If this is given proper publicity then I think this will put the criminal justice system into chaos.".

"We tend to challenge DNA evidence quite a lot because it involves a statistical interpretation of the figures and is based on opinion."

Key facts

A scientific analysis is carried out both on prints and all the ridge characteristics

Ridgology looks at the size of ridges, the flow of ridges and all the possible problems associated with the mark, pressure, angle and so on

The majority of prints in London are examined using an aluminium powder and lifted off by an adhesive tape

Prints are then scanned into computers and logged on a huge database with millions of others which cover the whole country. The computer is then able to match a print with ones taken at the scene of a crime

A print is considered a match when 16 ridges match up with a particular mark