Police hunting Mr Wilson's killer are carrying out DNA tests

People who were in the vicinity of Alistair Wilson's home in Nairn, north-east Scotland, on 28 November were asked to offer a mouth swab.

Tests began on Friday evening and will resume between 1200 GMT and 1800 GMT on Saturday afternoon.

The results will be compared to DNA samples found in the area.

The first swabs were taken at the town's police station where officers are hoping to see about 150 people before the operation concludes on Saturday.

The samples will only be compared against DNA profiles recovered during the inquiry and will be destroyed when the case is concluded.

Mr Wilson, 30, was gunned down on the doorstep of his home.

Detective Chief Inspector Peter MacPhee, in charge of the murder hunt, has promised the samples will be destroyed once the murder has been solved.

He said the tests are being carried out in order to eliminate people from the investigation.

Rewards offered

A spokesman for Northern Constabulary said: "There are about 150 people that we need to speak to. The samples involve a mouth swab and will be taken by police officers."

Despite an investigation involving 40 officers, two months after the shooting, the inquiry team has yet to find a motive for the killing.

The suspect was described as being aged 35 to 40 and was wearing a baseball cap and a dark blouson jacket.

In December, detectives confirmed that a handgun found in a drain near the scene was the murder weapon.

Police have been following up a number of calls after the case was featured on the BBC's Crimewatch programme.

Crimestoppers has offered �10,000 for anyone with information leading to the capture of the killer and a national newspaper has offered a similar reward.

Mr Wilson's widow, Veronica, said her life and that of her two young sons has been "torn apart" by her husband's murder.