"IT'Sjust unbelievable, " said the barman at the down-at-heel Windsor Hotel, around the corner from the shooting. "Things like that just don't happen here."

It was a common sentiment in Nairn yesterday as the Highland town faced its first weekend since the murder which has stunned this community and the surrounding region.

Shock; sorrow for the widow with two young children, now fatherless; and an overwhelming curiosity about the contents of a blue or green envelope which passed between the killer and the victim, and which police believe could hold the clue to the murder: a confusion of unfamiliar emotions is coursing through the town.

This is a respectable seaside town, a holiday resort which has somehow retained its clientele since Victorian times, where the numerous hotels, B&Bs and caravans fill up with families during the summer season, and where the allure of woodland walks, clean beaches, invigorating sea air and two championship golf courses has long ensured a steady supply of paying guests.

Now it is suffering the after-effects of a tragedy worthy of nearby Cawdor castle, made famous in Shakespeare's Macbeth.

Alistair Wilson, who ran a business banking team with the Bank of Scotland, was just 30 when his life was taken last Sunday. Together with his wife Veronica, 33, he had been putting his children, Andrew, four, and Graham, two, to bed when, at around 7.15pm, there was a ring at the doorbell of their sandstone villa in Crescent Road, in the town's centre. His wife, who answered the door, is still trying to piece together what happened next.

A man described only as clean-shaven, aged between 35 and 40 years old, of stocky build and wearing a baseball cap and a blouson jacket, asked for her husband by name.

Detective chief inspector Peter McPhee of Highland Constabulary described the events that followed as "horrendous".

"When Alistair approached the door he was what can only be described as brutally gunned down on the steps of his house.

"His assailant then made off, leaving Veronica to run to neighbours for help.

"There would appear to be absolutely no motive for this despicable crime."

Day by day, police are coaxing more information out of Veronica, who is understood to have been moved to a house in her native Fort William. So we learn that there was a brief discussion between the two men and, perhaps most significant of all, we learn of the existence of the mystery envelope.

"We are continuing to talk to her every day. She wants to help us much as she can, but she's still in a fragile state, " a police spokesman said yesterday.

"Things are coming back to her every day and she's able to help us a bit more each day."

Gradually it has emerged that, after two or three minutes' discussion between the two men on the doorstep, which Veronica only heard as muffled, Alistair brought the envelope into the house, apparently without opening it, and uttered what were to be the last words his wife would hear him say.

Police refuse to disclose what those were, although they admit that "reference was made to the envelope".

Alistair then returned to the door, where almost immediately he was shot three times, twice in the head and once in the body. He was taken to Raigmore Hospital in Inverness but died from his wounds. His killer was last seen disappearing down a road towards the seafront.

Alistair Wilson was a successful man and last year was involved in forming a new team for Bank of Scotland business banking. His role was to target small and medium-sized firms from Orkney to Oban, the Western Isles to Moray. However, he had apparently secured another job, and was due to leave the bank on Friday for the Building Research Establishment (BRE), a research and consultancy business, where he was to be commercial director in its new Inverness office.

Originally from Kilbirnie, in Ayrshire, Wilson joined the Bank of Scotland as an accountancy and business law graduate and started in the Fort William branch.

He moved to Edinburgh before joining the business banking branch in Inverness in November 1999. The family has only been in Nairn for around two years, and had set up their home as a hotel and restaurant, although the business was closed after a short while.

Police are combing through every aspect of his business dealings, although one woman familiar with his working life yesterday described him as "squeaky clean".

Inevitably, however, in the absence of hard information, the gap is being filled with rumour and speculation. Some say that the murder was somehow connected to personal issues, or that it was due to the fact that Wilson had uncovered some serious financial irregularities.

Similarly the envelope is subject to constant speculation. Was it filled with banknotes? As one Nairn man said sceptically yesterday, how much cash can you put in an A4 envelope?

Did it contain some sort of contract, perhaps a bank loan refusal? Or was it some form of blackmail note? Did the killer escape by boat? Speculation is rife, but nobody here has any answers.

"It's terribly sad, " said one elderly lady who was returning home after having done some Christmas shopping.

"Nobody has any idea how something like this could happen. And what about that blue envelope?"

Nairn is a mixture of commuter belt, retirement area and seasonal tourist town. A royal burgh since the 12th century, it has a sense of collective pride to match, although like most seaside towns it is wearing a little ragged in places.

Its Victorian heyday as a Highland spa town is spelled out in the lengthy promenade, built for bracing walks alongside the Moray Firth. However, the sandstone villas of the merchant class who once inhabited the town have since opened their doors to the modern-day professionals who make their living in the booming Highland capital of Inverness, a mere 13 miles west from here, and expanding ever nearer. The town's shops are feeling the pinch and an initiative has been launched to try to regenerate the town centre.

The A96 Inverness to Aberdeen road ploughs through the town, and most passing motorists' impression of Nairn will be an abandoned church and, opposite, the Regal lounge bar, which looks anything but.

Amid the fading grandeur, the peoplecarriers, the numerous churches and the bowling club, Alistair Wilson and his family must have epitomised the changing profile of this Brighton of the North.

Their home is not situated on some murky back street. Crescent Road is an affluent area: traditional stone-built villas similar to the Wilsons' are advertised in Nairn estate agents' windows for offers in excess of Pounds380,000.

The Wilsons' home stands directly opposite the Havelock House Hotel and its busy public bar. The house also stands near to the road end and the busy A96 Inverness to Aberdeen road. It is barely 100 yards from the police station around the corner. None of these facts seemed to perturb the killer.

Ron Stevenson lives directly across the road from the Wilson family home.

"We heard the ambulance, and I saw the police cordon up when I looked out the window at about 11pm, " he said.

"We didn't really find out what was going on until Monday morning - it's absolutely tragic.

"My heart just goes out to Mrs Wilson and the boys - it's an absolute sin."

Stevenson, who lives with his wife Kath, commutes to work in Inverness, just as Alistair Wilson did.

"We've been here about a year now ourselves, and it's not the sort of thing you expect to happen. I'm not worried for me - but I must admit that Kath was going to the gym the other day, and I walked her round. She usually goes on her own, but this has stopped that - at least for the time being."

In fact, people here seem to be getting on with their lives, as if there is a certain safety in the recognition that the killer was most likely not from within their midst.

The police appear to agree, since the killer felt the need to ask for Wilson by name. The spokesman added: "There doesn't seem to be this climate of fear in Nairn that's talked about."

For all that, this is not a Highland idyll.

It's a small town with the same problems that are associated with all small towns, a woman in the Havelock House Hotel bar said yesterday.

That fact was rammed home to her husband, a local businessman who asked not to be named, who was one of four people - the others were two policemen and an off-duty nurse - to go to the scene of the shooting last Sunday evening.

He had been in another local pub when a friend rushed in to tell him what had happened.

"I'd been there about 10 minutes when one of the people from the bar here came and said somebody had been shot. It took me about a minute to get to the door, it's something that just doesn't happen here.

"I ran down and saw what the situation was. It's one of those things that there's nothing you can do.

"What do you do for a man who's been shot in the head?"

The man, who moved to Nairn with his wife from England in April, was clearly still upset as he described the scene.

"I was one of only four people there.

The nurse was administering first aid, trying to help him breathe. I don't think the police knew what to do - it's not their fault, it's just not something they had come across."

The nurse, Tina Thompson, is still too traumatised to speak about the events.

"The be-all and end-all of it is that nobody seems to have seen the guy, " the local businessman added.

"Everybody's just trying to get over the shock. They put up the Christmas lights - everybody's just trying to get on with things.

"I feel so sorry for the family. It's Christmas and they'll be without their father."

Yesterday, the Havelock House Hotel was quiet - the presence of the police car sitting round-the-clock outside the Wilsons' house, which is sealed off with blue police incident tape, is not good for business. On Friday evening, although not jumping, the place seemed in full swing:

the cider was flowing, balls were clacking on the pool table and the jukebox was belting out AC/DC and Led Zeppelin. It was into this environment that Veronica Wilson ran last Sunday evening, desperately seeking help for her shot husband.

"It shatters the illusion of bliss, " said the local businessman's wife, who is five months' pregnant. "That's what it is, an illusion, now that Nairn has experienced this. People are shutting their doors, putting on locks when before they wouldn't bother."

The couple, who live very close to the Wilson family, did not know them personally. She said: "The tragedy is, we have a baby on the way and we might have got to know them."

The shock, and what they call the "adrenaline thing", is only now hitting the couple.

"It's the fatigue that goes with it. It's been hard for the people that grew up in Nairn and have known it all their lives. It's the harsh reality coming up here.

"But our stress is nothing compared to those involved. Things go back to normal for us, but they will never go back to normal for the family."