Barri White was jailed for the murder of his teenage girlfriend
Two men jailed after the murder of an 19-year-old woman could have wrongly been convicted by the flick of a lighter, Appeal Court judges heard.
In 2002, Barri White, of Bletchley, Buckinghamshire, was jailed for killing his girlfriend Rachel Manning in 2000.
Co-defendant Keith Hyatt, of Bedford, was cleared of murder, but found guilty of perverting the course of justice.
A link between the men and Ms Manning, said to be proved by particles from a lighter, is now being questioned.
Flint particles from a lighter were matched to Ms Manning's skirt after her disfigured body was dumped at Woburn Golf Club in Buckinghamshire, in 2000.
'Confused, imprecise, unreliable'
However, both men - whose cases have featured on the BBC's Rough Justice programme - have said they are victims of a miscarriage of justice and their convictions should be overturned as "unsafe".
John Coffey QC said forensic evidence had now been "heavily undermined" by fresh scientific experiments.
Central to the prosecution case was the evidence of geologist, Professor Kenneth Pye, who pointed to an unusual "assemblage" of seven particles found both on Ms Manning's skirt and the passenger seat of Hyatt's van, which was said to have been used to transport her body.
Two of the particles were flint debris from a disposable lighter which Professor Pye said provided "strong support" for a link between Ms Manning's skirt and Hyatt's van.
Keith Hyatt was found guilty of perverting the course of justice
However, Mr Coffey argued that further scientific tests since the trial, carried out by three experts, cast serious doubt on the reliability of Professor Pye's testimony.
Arguing that the evidence relating to the particles at trial was "confused, imprecise, unreliable and open to many interpretations", the barrister said a central plank of the prosecution case had been "heavily undermined, if not completely swept away".
Professor Pye's interpretation of the particles was quite simply "incorrect", he told Lord Justice Keene, Mr Justice Jack and Mr Justice Irwin.
It was the prosecution case at trial that said White strangled Ms Manning after an argument in Milton Keynes, then called Hyatt to help dispose of her body.
White insisted that he had left Ms Manning in Milton Keynes after the night out.
The Appeal Court hearing, expected to last at least two days, continues.