A scientific link between Mr Barry George and the scene of Jill Dando's shooting provided compelling evidence of his guilt, the Old Bailey heard yesterday.
Mr George is charged with the murder of Ms Dando outside her London home in April 1999.
A particle of discharge residue was found in the pocket of a blue Cecil Gee coat belonging to Mr George which probably came from a firearm, said Mr Orlando Pownall, prosecuting.
"The presence of lead in the particle from the defendant's coat pocket further supports that view, as does the similarity in the composition of particles from the defendant's coat and from the coat worn by the deceased."
X-Ray spectra of two of the particles found in Miss Dando's hair and the particle from the coat were "very similar in that they contain comparable proportions of the main chemical elements, barium and aluminium.
"The three particles from the hair and the single particle from the coat could all have originated during the firing of the cartridge that contained the cartridge case recovered at Gowan Avenue, [Miss Dando's home address]," said Mr Pownall.
He said fireworks also produced spherical particles of barium and aluminium. But they generally also contained other elements as well. Their absence in the particle recovered from Mr George's coat led a forensic scientist to conclude that the source was a firearm, rather than fireworks.
The prosecution also said it would have been difficult for the coat to have been deliberately contaminated with the particle.
"Great care was taken by the police, none of whom were firearms officers or had access to firearms," Mr Pownall said.