Detectives investigating the murder of Nairn bank manager Alistair Wilson say a potential witness has come forward.
Film of Alistair Wilson with his family was shown on Crimewatch
The call came after an appeal was launched on the BBC's Crimewatch television programme.
The 30-year-old was shot dead on his doorstep in the quiet Scottish seaside town on 28 November.
Detective Chief Inspector Peter MacPhee said police received a call from someone who saw a man fitting the description of Mr Wilson's killer.
Earlier, detectives confirmed a handgun found in a drain near the scene last week was the murder weapon.
DCI MacPhee said the Crimewatch appeal had yielded a number of interesting calls.
They included one relating to an envelope given to Mr Wilson at the time of the shooting, but which later disappeared.
A potential witness said they had seen a man with an envelope.
The suspect for the shooting is aged 35 to 40 and was wearing a baseball cap and a dark blouson
DCI MacPhee said: "I've had one very interesting call from a potential witness who saw a man answering the description of the suspect.
"This witness is the first we've spoken to who has seen anybody in possession of an envelope, so we're very interested in this witness."
Officers are still trying to establish a motive for the killing.
Police are examining CCTV footage from Inverness
Detective Superintendent Gordon Urquhart added: "We will now also be scouring CCTV footage from the bus station in Inverness where we have also received information that a man with a similar description was seen boarding a bus and alighting at Nairn.
"If CCTV is lucky enough to have caught this man on camera then I believe this will be another excellent boost to the inquiry."
He said the investigation was making progress and a clearer picture of Mr Wilson's life and business was emerging, which may lead to a motive for the killing.
Veronica Wilson, Mr Wilson's wife, was joined by his mother and sister during the Crimewatch appeal.
Since the shooting, Mrs Wilson and the couple's two young sons have been living under armed guard at a secret location.
During the Crimewatch programme, Mrs Wilson, who spoke off camera, described how she had answered the door to the killer. The man asked for her husband by name.
Jillian heard about her brother's death at her home in Australia
She left Mr Wilson on the doorstep with the man to go upstairs and look after their children.
"I heard the shots. I live in Nairn and this doesn't happen so I think it's someone breaking wood or something," she said.
"I leave the kids in the room and I run down the stairs."
She found her husband lying on the doorstep with the gunshot wounds which would prove fatal.
"I just can't imagine not knowing and being able to move on from here," she said.
"I need to be strong, these boys need to have a future but I can't give that to them until I have a better understanding of what's happened.
"We just need to catch this person and find out why they did this."
Mr Wilson's mother Joan and sister Jillian, who both appeared on screen, were brought to tears as they described their confusion over what has happened.
Jillian said: "Alistair was an ambitious, hard-working
man. A lot of people knew and respected him.
"He just adored his wife and just doted on his two wee sons. When I heard the news I was at my home in Australia.
"I jumped on a plane the next day and was able to be with my family, who are just so distraught at the moment.
Mr Wilson's mother also made an appeal on Crimewatch
"None of us know why this has happened - it is just a complete and utter mystery."
Joan added: "Veronica has lost her husband, these boys will never have a daddy that they will remember because they are so young.
"Not only that, but they have violated their home which they feel they are not happy to go back to.
"It's a complete upheaval in every way. We have lost our only son."
DCI MacPhee described how the gunman walked down Crescent Road towards the links area of the town where he is believed to have escaped.
He also reminded the public of the £10,000 reward on offer from Crimestoppers for anyone with information leading to the arrest, charge and subsequent conclusion of the case.
Northern Constabulary have set up an incident room to deal with the calls generated by the programme which can be contacted on 01463 720220.
Crimestoppers can be contacted on 0800 555111.