It is arguably Scotland's most baffling unsolved murder.
An affable 30 year old bank manager shot dead on his own doorstep by a mystery man who casually walks off into the darkness later dropping the murder weapon into a nearby drain.
An apparently motiveless execution in a quiet seaside town that left two young boys, now adults, without a dad and a grieving widow.
However could the killer who has remained free for almost 20 years finally be about to be brought to justice?
Alistair Wilson, then 30, was shot on November 28, 2004, outside his home in Nairn at around 7pm.
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He had been reading a bedtime story to his children - Andrew and Graham - when wife Veronica answered the door of their home to a man who asked for him by name.
Alistair came downstairs to speak to the visitor and was handed a blue birthday card style envelope with the word 'Paul' on it.
He showed it to his wife, and then returned to the door for a second time when the gunman open fired.
Veronica, hearing the three shots, rushed to the front door and then called an ambulance.
She then ran across the road to the Havelock Hotel for help where the pub's chef, an off-duty nurse and owner Andy Burnett went to her aid.
Alistair, pictured with his wife Veronica
The publican Andy Burnett at one point stopped the dying dad from slipping off the stretcher and fixed his watch as it came loose before comforting Alistair's traumatised wife.
An ambulance took Alistair to Raigmore Hospital in Inverness, where he died an hour later.
After his murder, police started to delve into the victims past to see if there was anyone who might have wished him harm.
However a picture quickly emerged of a fun-loving, loyal and generous man with few, if any, enemies.
At the time, Detective Chief Inspector Peter MacPhee, of Police Scotland, confirmed:"We have not found a dark side to him. If there was, we would have expected to find it by now."
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Alistair's sister, Jillian Bynon later said:"He was a person who was able to make me smile, tell me a funny story, make me laugh, my special little brother."
At the time of his murder Alistair had resigned from the the Bank of Scotland, and was due to begin a new job in Inverness with an environmental consultancy firm.
Despite exhaustive searches of his professional life, police could turn up nothing that suggested Alistair had left under a cloud or any links to his work at the bank.
He had been born in March 1974 in Beith, Ayrshire and had studied accountancy and business law at Stirling University before joining the Bank of Scotland as a graduate trainee in 1996.
His first work posting was to Fort William, where he met graphic designer Veronica MacDonald.
Alistair and Veronica on their wedding day
It was a whirlwind romance with the couple engaged within six weeks of meeting.
The couple settled in Nairn when Alistair was made business manager of the Inverness Bank of Scotland branch.
He was responsible for securing the custom of small-to-medium sized companies across the North of Scotland.
The couple bought the family home on Crescent Road in 2002 and ran a restaurant from there at one point.
Police traced other Alistair Wilson's to see if he was the victim of mistaken identity.
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One man with the same name lived just two minutes away but could not be linked to the crime. Nor could any others.
Attention focused, too, on the mysterious envelope, which the killer appeared to have taken away with him.
However they were baffled as to what it might have signified. Who was Paul and why was the envelope empty? No men of that name in the immediate area had any link to Alistair.
It seemed to mean nothing to the victim, whose wife had confirmed his bewilderment when he showed it to her.
Ten days after the murder police thought they had made the vital breakthrough that all such inquiries need.
Alistair's son, Andrew, aged 20
An antique German pocket pistol, used to kill Alistair, was found in a drain half a mile away by council workmen.
However, when forensic experts examined the gun, no forensic evidence was found linking it to any individual.
The killer had simply vanished as quickly as he had arrived and had not been picked up by local CCTV cameras.
The only clue to his his identity was a description of a man about 5ft 7in tall and wearing a baseball cap and jacket.
In 2005, detectives took the unusual step of hypnotising Veronica to take her back to the moment her husband was shot and hopefully provide new details that might identify the gunman.
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Though the process was useful it did not provide any significant new lines of inquiry.
Over the following years the investigation appeared to stall as information began to dry up prompting ever wilder theories involving organised crime, dodgy bank dealings and even an IRA hitman. All were rubbished by the police at the time.
In 2020, Alistair's eldest son Andrew, by then 20, made an appeal for new witnesses to come forward, highlighting how the devastating loss of their father had affected him and his brother.
He said:"There would be no more bedtime stories, no more playing football or helping him in the garden. My dad and I missed out on so many things together."
However in April last year police made a series of dramatic announcements following a cold case review.
They revealed that a 2004 planning dispute was now at the centre of their investigation.
Shortly before his murder Alistair had objected to a large decking area which had been built outside the Havelock Hotel.
Owner Andy Burnett received a copy of the letter from the council only two days before Alistair's murder.
Detectives had also travelled to Nova Scotia in Canada in February to interview Burnett about the dispute, though later stressing he was a witness and not a suspect.
The 55-year-old had emigrated in 2013 with his wife Lynn, 48, and family after selling the hotel.
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Police Scotland also revealed that two men were seen with a handgun on Nairn's East beach, just a month prior to Alistair's murder.
The younger of the pair, a man in his 20s was handling the weapon, and the other was aged between 40 and 60 years old.
Police Scotland also issued an appeal to Havelock Hotel customers, who were there in the days leading up to Alistair's murder, to come forward, particularly if they had heard anything untoward.
Could something as mundane as decking erected without proper planning lead to a man's murder?
Burnett had subsequently applied for retrospective planning permission for the decking which his neighbour opposed.
In the letter, which was prickly in its content, Alistair, said:"The decking has been used for the service of food and drink whenever the pub is open.
"This has included late nights with the bar doors open and the consequent noise and disturbance.
"Further on a regular basis I find glasses in my garden and broken glass strewn in the street.
"During the summer months, I and my family felt uncomfortable using our front door and even looking out our front windows during the hours the pub was open as we frequently had customers staring back at us."
Alistair also mentions in the letter that he had a prior conversation with Burnett, who he used to play golf with, about the decking issue.
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Last year Detective Superintendent Graeme Mackie, who was by now leading the investigation, said of the planning dispute: "I know it's really difficult to try and comprehend but that is the only aspect that we can see in Alistair's life that was causing upset.
"The Havelock pub at that time was a really popular venue.
"People were invested in this decking. People who attended that pub helped build it. They took a lot of pride in it."
Mr Mackie then added:"There was a level of conversation within the pub being upset towards Alistair complaining about it and the potential that it could be taken away.
'We want to find out if, during that weekend, anybody was making any threats. "Was anybody speaking disproportionately about taking action against Alistair, demonstrating a level of real concern that would suggest Alistair may well be coming to harm at some point in the future?'"
In the last year a local man, probably now in his 40's, has emerged as a possible suspect in the case.
A regular in the Havelock Hotel at the time of Alistair's murder, he was said to have access to firearms.
The man, who cannot be named for legal reasons, is currently serving a prison sentence for drug offences.
Another theory that has emerged recently was that two men, not one, were involved in the murder.
One acted as bait to lure Alistair to the door because the killer, being local, did not want to be recognised.
The drain where the murder weapon was dumped would have been at the passenger side of a possible getaway vehicle.
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Police Scotland insist that despite the passage of time they are still dedicated to solving the case.
Detective Chief Inspector Graham Smith said:"The investigation into the murder of Alistair Wilson is active and we continue to investigate any new information we receive.
"It cannot be stressed often enough that this crime has left a family devastated and Police Scotland is committed to finding the answers for them and bringing the offender to justice."
Retired Metropolitan Police detective Peter Bleksley, who has written a book about Alistair's murder, To Catch A Killer, is concerned that things have gone quiet on the investigation in recent months.
Bleksley, who hosted the hit Channel Four series Hunted and never worked on an unsolved murder, is however convinced that Alistair Wilson's killer can be finally brought to justice
He told the Herald:"I have always held the view that this is a case which could and should be solved.
"The police clearly have someone in their sights.
"I was in Nairn in June and the murder is still a hot topic of conversation.
"It needs to be solved not only for Veronica and the children but also to finally bring closure to the town itself."
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