Forensic tests revealed there was no DNA evidence linking a pair of blood-stained jeans with a man accused of murder, a jury at Lewes Crown Court heard.
Robert Cairns, 27, has denied killing Justin Hayward on Brighton seafront in 1996. The jeans were stained with Mr Hayward's blood.
Mr Hayward, 19, from Copthorne, near Crawley, who had been treated for leukemia, was stabbed 40 times in the throat, neck and eyes during a frenzied attack at Duke's Mound.
The jury heard Cairns and a friend, Paul Maynard, stood trial for the murder in 1998. Cairns was convicted of the killing while Maynard was convicted of the less serious charge of causing grievous bodily harm.
But the Court of Appeal later quashed Cairn's conviction and ordered a re-trial.
On the second day of the re-trial the jury heard new DNA tests were carried out earlier this year on the waistband and pockets of the jeans, which were found in Maynard's room at a hostel in Marine Drive, where all three men were staying.
There was no scientific evidence to connect Cairns with the jeans but the results showed they could have been worn by Maynard.
Home Office forensic scientist Hazel Johnson said: "Given the circumstances and the evidence of DNA it is probably more likely Mr Maynard wore the jeans at the time the blood came to be deposited upon them."
The court heard Maynard had previously denied ever owning or wearing the jeans.
Earlier the jury was told there had been a dispute over sharing a beer between the three men. Mr Hayward's body was found by a passerby on October 19 four years ago. He had been punched and kicked while on the ground as well as being stabbed.
The trial continues.
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