Police investigating the murder of the Nairn banker Alistair Wilson say they are making a "last throw of the dice" in a bid to obtain vital forensics.
Alistair Wilson was gunned down on his doorstep in November last year
The 30-year-old was shot dead on his doorstep last November.
The gun used was later found in a roadside drain in the town but tests have so far failed to provide any positive leads.
Northern Constabulary have now taken swabs from inside the weapon and its mechanism in a bid to find DNA.
However, the man in charge of the inquiry said he was not hopeful the additional tests would yield anything new.
Detective Chief Inspector Peter MacPhee admitted he was making a last attempt to get DNA evidence from the small automatic pistol.
He said: "External swabs taken from the gun produced very limited results.
"Another batch has now been taken from the internal mechanism of the weapon and have been sent away to see if there are any traces of DNA.
"The second batch of swabs may or may not provide leads, but we feel at this stage we have nothing to lose getting these tests done.
"But it is highly unlikely to yield anything. As far as getting forensic evidence from the gun is concerned, this is our last throw of the dice."
Despite the lack of evidence from the murder weapon, DCI MacPhee remained confident of catching the killer of the father-of-two.
He said the gun was only one of many lines of inquiry still being investigated.
Mr Wilson, a business banking manager with the Bank of Scotland in Inverness, was shot on his doorstep at about 1900 GMT on Sunday, 28 November, by a caller to the house.
The killer, who was holding a blue or green envelope, knocked at the door and spoke to Mr Wilson's wife, Veronica, asking for her husband by name.
She went for Mr Wilson, who had been putting their two children to bed, and minutes later shots were fired.
The gun was recovered 10 days later from a drain less than a mile from the home.