A little more than 16 miles from Inverness, along the Moray Firth, lies the resort of Nairn, genteel in manner and close-knit in nature. It is a community of 11,000, a place where an outsider might imagine no one is a stranger, and all are friends.
In years gone by, its fine weather - by the standards of north-east Scotland - made it a favoured destination for wealthy Victorians. Nairn now hosts weekend sailors rather than the busy fisher-folk who used to make it such an important port.
Crime? Only the odd instance of graffiti or the rare outbreak of fisticuffs on a Saturday night which blight even the smallest village in 21st century Britain. The local police station is hardly over-worked.
Murder? There was one back in 1986. Prosaically, it arose out of an argument at a wedding party. And so it was in Nairn - until exactly one year ago.
Then, inexplicably, unbelievably, Alistair Wilson, 30, a local bank manager who had two children, was executed on the doorstep of his home by the sea and yards from the town centre. Just moments earlier, he had been bathing his boys.
It is a crime that has rocked a community and left Northern Constabulary foundering despite spending £1m on the biggest investigation ever by the force. Twelve months on, police are baffled - and, despite their best efforts, it seems the trail is growing colder by the day.
More than that, Nairn has lost something - its innocence perhaps, its confidence certainly. And each day that passes does nothing to soothe the fears or render understandable the incomprehensible.
Wilson, 30, had been born in Ayrshire but moved to Nairn with his wife, Veronica, and sons, Andrew, now six, and Graham, three, just a couple of years ago.
Working at the Bank of Scotland as a business manager, he made sure he was back from work in time for tea with the family and read bed-time stories to his boys. He loved Nairn for the peace and quality of life it gave him and his family - and anyone wandering along the sand dunes past the swings and that bandstand could surely see what he meant. To all who knew him, he was a happy, settled man.
And then came Sunday 28 November 2004.
Just like any other weekend, the Wilsons had met up with friends, gone for a walk in the woods close to their home. They spent some time with the boys at the swings there. Mrs Wilson, 33, takes up the story: "When we got home Alistair went to the supermarket, did the recycling and started getting the boys ready for bed. He was just settling down to read a story to the boys when the doorbell rang. I answered it and there was a man I didn't know who asked to speak to Alistair." She said her husband seemed surprised, as he wasn't expecting anybody. She left the two talking as she went upstairs to continue putting the children to bed.
The man gave Alistair a turquoise-coloured envelope, which has never been found. Nobody knows whether the victim opened it or knew what was inside. Police believe it must have been highly significant because the killer took it with him.
"We thought it was strange but there was no sense of danger or threat," said Mrs Wilson.
Mr Wilson popped back in briefly, and told his wife he did not know the man. Then he went back outside. Seconds later, three shots rang out and the banker was left dying in the doorway.
Despite the best efforts of up to 63 officers - who have taken 2,972 witness statements, checked out 6,104 names, visited 383 homes, collected 202 DNA samples, interviewed 3,784 people, checked 568 vehicles, examined 1,195 documents and travelled the length of the UK - the murder remains a mystery.
There have been no shortage of theories, many debated at length in Nairn's workplaces, its shops schools and pubs. There was one of the colleague with a grudge, and speculation that he had denied a no-nonsense businessman a loan. Was it a contract killing, with the intended victim another Alistair Wilson? Was there an extra-marital affair somewhere, a crime of passion? Detective Chief Inspector Peter MacPhee explains: "The question of possible infidelities was something we had to look at, but there was nothing. We have not found a dark side to him. If there was, we would have expected to find it by now."
Although the weapon used, a German handgun dating from the 1920s, was later found, it has so far provided police with little information. But it is rare, a semi-automatic made by Haenel Waffen of Suhl, and the even more unusual origin of the Czech ammunition used, gives officers hope that it could help.
Officers have already carried out inquiries across Scotland, in several parts of England, Northern and the Republic of Ireland, the Channel Islands and mainland Europe. They are now planning to travel to Germany and the Czech Republic.
But at least one top forensic psychologist fears the murder may never be solved.
Ian Stephen, the Edinburgh-based expert who was an adviser on the Cracker and Prime Suspect television shows, says: "The longer it draws away from the first few days the more difficult it is to catch the killer because people's memories tend to change and the trail gets cold.
"This particular murder is unusual because you have a crime where there is no indication or links to why it would happen. With most you can see some connections, but not in this one. The police are at the stage where they have exhausted all possibilities and are just hoping and praying that something will turn up."
Mr Stephen says the crime exhibited "unusual features", such as the caller coming to the door. "If he had been a professional hitman, I do not think he would have been as obvious as that. And I don't think it was mistaken identity, because he asked for Alistair Wilson by name."
He believes that similar crimes were usually related to drugs or money laundering, where someone had a particular problem or grievance. "In such cases though, whoever is behind it is normally traced within a few days as the reason for the killing emerges pretty quickly. In this case, though, there is no one in town that knows anything about it. It is one of the great unsolved mysteries - it is baffling."
Earlier this month police released part of the 999 call made by a hysterical Mrs Wilson immediately after the shooting, along with video footage of Andrew Wilson being told his father was dead, in the hope of stirring someone's conscience. So far, more than 30 people have contacted police with new information and the names of at least two known criminals.
"All it takes is one phone call or piece of information to give us that vital breakthrough," says a spokesman for the Northern Constabulary, which recently appealed for 150 people whose DNA profiles were found in the area immediately after the shooting to provide samples so they could be eliminated from the inquiry. "We have managed to obtain DNA from the vast majority of people but a handful have still to come forward," says the spokesman. "If any of those who have not yet volunteered are ever matched with the DNA we have, then they will have a lot of explaining to do as to what they were doing in Crescent Road and why they haven't come forward. It is quite possible that the killer's DNA is among those we have not matched yet."
It is understood unidentified DNA traces from a cigarette butt found close to the murder scene is of particular interest to police.
Officers have also used a hypnosis-style technique on Veronica Wilson. The regressive cognitive technique involves experts putting certain types of questions to probe the mind and help bring forgotten information to the surface. "We got a far more detailed account of what happened, building a more accurate picture for us. I believe we got as much as she was able to remember," says the spokesman.
For Mrs Wilson, who remains in the family's traditional town-house in Crescent Road overlooking the Moray Firth, the technique was another straw to clutch at. "Albeit the anniversary, it is with us every day," she said yesterday. "It is still very unreal and I feel it will be until someone is captured and we can be left to grief without the police presence.
"There is still a murderer out there and he still needs to be caught. If I didn't have the boys I don't know what I would do."
All callers to the house, even the police, are referred to the back door away from the spot where her husband was killed. For months, there has been speculation among the uninformed, in the absence of any other obvious motive, that his killer could be closer to home.
Mr Wilson didn't leave a will, which meant his widow had to submit a formal application at Inverness Sheriff Court to be appointed executor of his estate. As a result of his death she inherited more than £130,000 - including his half share in their jointly owned £230,000 luxury home, £6,243.91 from personal bank account, £4,940.04 from bonuses due to him from the Bank of Scotland, a further £2,600 from her husband's saving schemes and income tax rebates and £2,000 of furniture and personal belongings.
DCI MacPhee admits: "It would be reasonable for most folk to expect us to look at whether Veronica Wilson was involved somehow and we did. But I can say we have investigated the immediate Wilson family and the extended family of Veronica very closely and there is no evidence at all to implicate any of them either directly or indirectly with Alistair's death."
Mrs Wilson admits she can see why others would consider her a suspect, but claims it is only because they know nothing of the loving relationship she had with her husband. "I find it hard to believe that people out there actually think I had anything to do with this. How could I take away my two sons' father?"
For his children, the pain of losing their father is still emerging. Last weekend, Andrew, the elder boy, attended a special holiday camp with other children of murder victims. He took with him a memory jar and a cuddly toy.