Two men were seen with a handgun near the town where a bank worker was murdered, according to new police information.
Alistair Wilson, 30, was shot and killed at his home in Nairn in November 2004.
Detectives investigating his death said they remain committed to finding out who killed him.
Following recent appeals for information, a witness reported seeing two men, one aged in his 20s and the other between 40 and 60 years old, on East Beach about a month before the shooting.
The witness said the younger man was in possession of a handgun.
Detective Superintendent Graeme Mackie, of Police Scotland’s Major Investigation Team, said a new appeal with this information has been launched to help officers identify the two men.
He said: “We are following up this new information and I would ask anyone with information, or who may be able to identify the men, to please come forward and speak with us.
“This potential sighting was passed to officers following recent publicity around the case and I am grateful for the positive response we have received from the local community.
“As I have said recently, time is no barrier to justice. More than 17 years have passed since Alistair’s murder, but Police Scotland is committed to bringing his killer to justice and providing the family with the answers they deserve.
“Someone out there knows what happened to Alistair and developments in the investigation over the last few weeks are a vital reminder that it is never too late to come forward with information, no matter how small or insignificant you may think it is.”
Detectives believe the man who shot Mr Wilson was aged between 20 and 40 years old at the time, which would mean he would now be in his mid-30s to almost 60 years old.
He was approximately 5ft 7in tall and was wearing a baseball cap and jacket.
Mr Wilson was shot at about 7pm on Sunday, 28 November 2004, after a man called at the family’s home on Crescent Road, Nairn, and asked for him by name when his wife Veronica answered the door.
Mr Wilson went downstairs to speak to the man and was handed a blue envelope with the word “Paul” on it.
He went inside briefly and then returned to the door for a second time when he was shot.
Officers said anyone who believes they can assist police is asked to contact 101 quoting incident 515 of 4 March 2022 and Operation Sorn or you can e-mail a dedicated inbox at SCDHOLMESAberdeen@scotland.pnn.police.uk