Detectives investigating the murder of Nairn banker Alistair Wilson say a number of unidentified DNA profiles could reveal his killer's identity.
Alistair Wilson was shot dead on his doorstep
Detective Chief Inspector Peter MacPhee, leading the inquiry, said he could not rule out the possibility one of them belonged to the lone gunman.
The 30-year-old father of two children was gunned down on his own doorstep in Nairn last November.
Mr MacPhee said his 29-man inquiry team was determined to solve the case.
This Sunday will mark six months since Mr Wilson was killed. Detectives say they have kept his widow, Veronica, up to date with their investigation.
POLICE MURDER INQUIRY
5,000 names in police system
2,500 statements taken
214 DNA samples
Mr MacPhee said: "A great deal of work has already been done, but much remains to be done. A number of specific lines of inquiry are being followed.
"We continue to liaise with Veronica on a regular basis and keep her abreast of developments."
Referring to the DNA profiles, Mr MacPhee added: "While they may be there quite innocently, I cannot rule out the possibility that one of them may be the profile of Alistair's killer."
More than 40 calls have been received following Mr MacPhee's second appeal for information on the BBC's Crimewatch programme in April.
He said: "We are still following up calls from members of the public resulting from media appeals including the Crimewatch appeals, and interviewing people who either knew Alistair or had some form of contact with him."
Mr Wilson's killer used a Schmeisser semi-automatic pistol, of which about 40,000 were originally manufactured.
The gun is small enough to fit into the palm of a hand and police believe it may have been brought into the UK during or after World War II.
The pistol was found in a drain about half a mile from Mr Wilson's home where he lived with his wife and sons.