Fingerprint evidence is fallible

Businessman Alan McNamara was sentenced to two and a half years in prison for a burglary he says he did not commit. The evidence linking him to the scene of the crime was a single thumbprint. Shelley Jofre reveals there are flaws in the evidence against him.

For a century fingerprints have been regarded as indisputable evidence. It carries so much weight as evidence that lawyers often advise their clients to plead guilty if they cannot explain how their prints came to be found at a crime scene.

But the police admit fingerprint experts are fallible. Commenting on other cases, Chief Constable Ben Gunn says, "It may be an identification, but it isn't fact, it is opinion."

Alan McNamara says he had not visited the scene of the crime

Last month Alan McNamara was convicted at Manchester Crown Court. It took the jury just two hours to reach a unanimous guilty verdict.

The thumbprint found at the scene of the crime was the only evidence to link McNamara to the burglary. But defence experts argued that the print could not have been taken from the surface where police say it was found.

Expert witness

American fingerprint specialist Pat Wertheim was one of the experts who testified on behalf of McNamara. He was shocked at McNamara's conviction.

Pat Wertheim was shocked at McNamara's conviction

He says, "Never in my wildest imagination did I think that a jury could convict with no evidence whatsoever except one single fingerprint which in itself is flawed."

He adds, "I know I'll be criticised for speaking out against the system like this, but I'm staking my reputation on this case and I know I'm right. I invite fingerprint experts from all over the world to look at the case, look at the information, look at the lift if they can and form their own opinions."

Wertheim and British expert Allan Bayle looked at the print and agreed it definitely belonged to Alan. But they said it could not have been taken from the wooden jewellery box where the police said it was found.

There was no visible wood grain in the print, and its shape indicated it was taken from a curved surface, not a flat one. In court Greater Manchester Police's experts argued that their expert had a different technique for lifting prints, and that the box had been dirty. The jury believed them.

Wertheim says, "If Greater Manchester Police has developed such a technique they've failed to publish it, get it peer reviewed, have it examined by any other expert outside of their agency."

Miscarriages of justice?

Panorama has compiled a dossier of cases where convictions have been overturned when fingerprint evidence has been shown to be flawed.

Chief Constable Ben Gunn says fingerprint evidence is taken as fact

Chief Constable Benn Gunn of the Association of Chief Police Officers accepts defence teams rarely challenge fingerprint evidence in court, where it is usually taken as fact.

He says, "It is not evidence of fact. It is evidence of opinion, and human beings see different things, experts see different things."

Gunn says that no bureau has yet apologised for mistaken expert opinions. He says, "Experts are jealous of that opinion, and nobody likes to think they've made a mistake."