The man jailed for Jill Dando's murder is discussing with his solicitor how evidence obtained by the BBC's Panorama programme might help his appeal.
Firearms residue expert Professor Marco Morin told the show that scientific evidence against Barry George should never have been used at his trial.
He said a particle found on his coat may not be from a gun, as was believed.
The Criminal Cases Review Commission is currently considering whether to refer the case back to the Court of Appeal.
Panorama will submit its evidence to the commission, which has been commissioning forensic tests and interviewing a number of witnesses for the past two years and expects to reach a decision "in the near future".
George's coat was found a year after the BBC presenter was shot once in the head in Fulham, west London, in 1999.
The attack on Jill Dando was carried out by somebody who was clearly... trained to use a converted weapon in the only possible way it could have been used, which was right up close at point-blank range
John O'Connor, the former Commander of Scotland Yard's Flying Squad
It was taken from its evidence bag and photographed at a police station before being examined by forensic scientists.
A witness, a retired reverend, says he saw police entering George's flat with guns - which may have contaminated the scene - when they took the coat away.
This has been denied by the police.
But now Professor Morin says the particle was more likely to have come from an incinerator burning paint or from somebody arc welding.
On Tuesday, George's solicitor, Jeremy Moore, told BBC News he had also given the commission three psychiatric reports.
All of the experts agreed George - a loner with learning difficulties - was clearly incapable of committing the crime, he added.
"They describe him as shambolic and unable to carry out simple instructions - particularly not a professional hit in broad daylight."
John O'Connor, the former Commander of Scotland Yard's Flying Squad, told BBC News: "Frankly, anybody looking at that case would realise the attack on Jill Dando was carried out by somebody who was clearly professionally trained, trained in close quarter combat, trained to use a converted weapon in the only possible way it could have been used, which was right up close at point-blank range."
Convicted two years after the murder, George lost an appeal in 2002.
Speaking from prison, he told Panorama he had had nothing to do with the murder.
"I have got evidence to show that," George added.
Many people signed a book of condolences following the killing
George, who lived just half a mile from Miss Dando's home, had a previous conviction for an attempted rape.
The Panorama programme also features an interview with a juror from the original 2001 trial, who expresses her doubts about the validity of the guilty verdict.
Janet Herbert told the programme: "I just felt shocked that on that little evidence anybody could be locked away for the rest of their life."
On Tuesday, a Metropolitan Police spokesman told BBC News: "This case was thoroughly investigated and the evidence put before a jury, who convicted Barry George.
"A number of other matters were also raised before the Court of Appeal, which upheld the jury's decision.
"This case is now under review by the Criminal Cases Review Commission, to whom the Metropolitan Police Service continues to lend its fullest support.
"Our thoughts remain with the family and friends of Jill Dando."
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.