Forensic analysis questions the only piece of scientific evidence against the man jailed for murdering Jill Dando, the BBC's Panorama has found.
Barry George has always denied he murdered Ms Dando
Firearms residue expert Professor Marco Morin says the single particle taken from Barry George's coat may not have even come from a gun.
He says it should not have been introduced as evidence.
George was convicted two years after the BBC presenter was shot once in the head in Fulham, west London, in 1999.
A juror has spoken publicly for the first time of her feelings about the guilty verdict reached in July 2001.
Juror Janet Herbert says: "I just felt shocked that on that little evidence anybody could be locked away for the rest of their life."
The jury was put up in a hotel during a weekend because the members were unable to reach a verdict.
A second juror who wished to remain anonymous says that some of the deadlocked jury talked about the case at the hotel.
'Excluded from discussions'
This was specifically against the judge's instructions.
These instructions are meant to stop subcommittees forming cliques that could influence the final decision.
Janet Herbert felt excluded from these discussions.
Reporter Raphael Rowe investigates whether there is new relevant evidence the jury should have heard. He had exclusive access to case documents and exhibits.
Barry George's coat was found a year after the BBC presenter's death and was taken from its evidence bag and photographed at a police station before it was examined by forensic scientists.
A witness, a retired reverend, claims that he saw police entering George's flat with guns when they took the coat away but this has been denied by the police.
Many people signed a book of condolences following the killing
This may have contaminated the scene.
Professor Morin suggests that the particle may have come from an incinerator burning paint or from somebody arc welding.
Panorama finds out that the jury members were never given information explaining why Barry George was desperate to establish an alibi for the time Jill Dando was shot dead in the head on the doorstep of her home in London in 1999.
George had been questioned about the Rachel Nickell murder on Wimbledon Common in 1992.
He had nothing to do with that murder but he was afraid that he would be questioned again. Trying to establish the alibi made him look highly suspicious.
One witness, Susan Bicknell, tells the programme that she could provide George with an alibi but she suffered a nervous breakdown after the trial and fears her illness made her a poor witness when she took the stand.
Contrary to the media coverage and prosecution case that George was obsessed with Jill Dando, there were only eight newspaper articles about her found in the stack of 800 newspapers in George's house.
None of the stories about her had been highlighted or clipped out or stuck on a wall.
A friend says that George never spoke about Jill Dando until after her death.
For the past two years, the Criminal Cases Review Commission has carried out a review of the case.
It says this has involved commissioning forensic tests and interviewing a number of witnesses and expects to make a decision about whether to refer it to the Court of Appeal "in the near future."
George lost an appeal in 2002 and remains in jail.
Panorama will submit its evidence to the commission.
Jill Dando's Murder: The New Evidence will be broadcast on Tuesday 5 September at 2100 on BBC One and streamed live at bbc.co.uk/panorama.