Forty years on from the murder of an Aberdeen taxi driver, police say they have made their most significant development in the case to date.
58-year-old George Murdoch, also known as Dod, was found dead beside his taxi in Pitfodels Station Road in Aberdeen on 29 September, 1983.
A cheese wire had been used as a garrotte during the attack.
Police have revealed they now have what they believe is the DNA profile of his killer.
Det Insp James Callander told the BBC they are using the DNA to check "persons of interest" that have emerged over the four decades..
"The forensic scientists have managed to develop this profile from various crime scene material. A lot of names came to the fore over those 40 years. Obviously never a suspect but people we would class as persons of interest," he said.
"We've been able to eliminate most people that have come into the inquiry. It's now at a natural time where we need the public's help."
The DNA profile is male but police warn that it alone will not solve the crime. They need to find a match to the sample and are now appealing for help from the public, including people who may suspect they were related to the murderer.
Det Insp Callander said: "Forty years on the chances are the male responsible could be dead, so we're looking at sons and daughters who maybe had suspicions over the years that their father was responsible to come forward.
"We can take a simple DNA swab and we can compare that to give peace of mind to the family to say your father isn't responsible."