Detectives investigating the murder of an Aberdeen taxi driver in 1983 say they remain "optimistic" the killer will be identified.
George "Dod" Murdoch, 58, was found dead beside his car with a cheese wire garrotte lying nearby.
Police Scotland said the public continued to come forward from around the world.
Det Insp Gary Winter, of the force's major investigation team, said he was "hopeful" that advances in forensic science could ultimately prove crucial.
He said the level and range of information coming in from people was surprising, with more than 100 new contacts being made from the public.
He told BBC Scotland: "I remain quite optimistic that with the public's help we can identify the killer.
"People still remember this crime from so far back.
"I cannot imagine the killer is the only one who knows who is responsible."
He said relatives of Mr Murdoch were "really driven" to get justice.
Mr Murdoch picked up a "random" fare in Aberdeen's west end and told his control room he was heading to Culter on the evening of 29 September 1983.
He never made his destination.
About two miles into the journey, it appears Mr Murdoch turned off onto Pitfodels Station Road, just on the outskirts of the city, where he was assaulted.
Two cyclists saw Mr Murdoch being attacked and phoned the police from a nearby hotel, but when officers arrived it was too late.
His wife Jessie - who died in 2004 - worried about his safety, but he told her he would never resist a robber.
His money and wallet were stolen in the attack.