Dando defence case casts doubt on vital speck of gunpowder

A crucial piece of evidence in the Jill Dando murder trial may have been accidentally contaminated by the police, a forensic science expert admitted yesterday.

A coat containing a minute trace of gunpowder seized from the home of Barry George ­ who is charged with shooting the television presenter ­ may have been "compromised" with other substances at a photographic studio, an Old Bailey jury was told.

An incriminating particle was discovered inside the pocket of the coat belonging to the 41-year-old suspect, who denies the murder charge, when examined by the police. The prosecution claims the sample could have come from the gun that was used to shoot Ms Dando, 37, through the head at Gowan Avenue, Fulham, west London, on 26 April 1999.

The coat was first taken to a police photographic studio before being sent to a forensic laboratory. The studio had previously been used to photograph a suspected terrorist's gun and six rounds of ammunition from unconnected cases, the jury has been told.

None of the surfaces or the tailor's dummy in the studio had been tested for firearms residue before the coat was photographed. The cleaning of the area was "intermittent" and "not very thorough", the jurors were told. Robin Keeley, a forensic expert who later tested the coat, said: "It is possible the integrity of the garment has been compromised."

During his cross-examination, Michael Mansfield QC, defending Mr George, said there were several "factors" involving the handling of the coat, which, when put together, "seriously compromised" its integrity.

Mr Keeley admitted when he examined the garment that he had no idea it had been used in the photographic studio. He said: "It is something I wish hadn't happened. It was unnecessary. I wanted to examine it in the laboratory first." Mr Mansfield asked: "When this coat was photographed, a particle of firearms residue could have remained in the studio, couldn't it?" Mr Keeley replied: "Yes."

Mr Mansfield reminded jurors how the coat had been laid on an untested exhibits box. Mr Keeley said: "I wouldn't say the integrity of the garment has been seriously compromised... It is just possible [that] it has been compromised."The jurors were told how a gun holster seized from Mr George's home last May was tested but no gunfire residue was found.

The trial continues.