New forensic evidence has been found in a murder inquiry in Oxfordshire that has been unsolved for 20 years, Thames Valley police have revealed.
The body of Leonard Gomm, 75, was discovered by a lorry driver on a grass verge in the village of Hampton Gay, near Bletchingdon, on 13 June 1990.
Officers believe the taxi driver had picked up a fare from Gloucester Green, Oxford, at about 0615 BST that day.
His vehicle was found nearby and he had been stabbed to death.
Det Supt Barry Halliday, of Thames Valley police, said the new forensic information was "crucial" and could link the killer to the scene of the crime.
"Members of the public can be assured that this evidence will also allow us to eliminate anyone not responsible from our inquiries, so even the smallest piece of information they have, even if they think it is insignificant, may help us find the person responsible."
Mr Gomm's daughters - Susan McCarthy, Sandra Gomm and Angela Cook - said they were still suffering from his loss.
They added that he should have enjoyed his later years with his wife, who has since died.
A statement read: "They should have enjoyed their children and their grandchildren.
"He was no threat to anyone. There was no need to attack him so violently or inflict such vicious injuries."