FOR the past 30 years, Willie Anderson has scoured vast areas of the Cairngorms, solving more than 1,200 cases of missing people. Most of the time, the search ends in an emotional reunion, but inevitably there are cases when the Cairngorm Mountain Rescue Team leader only recovers a body.
What all 1,200 cases have in common is that Mr Anderson and his team always manage to track down the person they are looking for.
But there is one case that remains unsolved, one person not located.
It is a mystery that nags away at the 52-year-old, that one unsolved case in a sparkling 30-year-career in the rescue business.
At 3:40am on 21 January, 2008, several hours in to his 47th birthday, family man Steven Cooper got in his car outside his home in Golcar, Huddersfield. He has not been seen since that day.
His Ford Focus was found a week later on the A86 about 20 miles north-east of Fort William. Fuel receipts found in the car show that he drove up the A1 into Scotland and eventually stopped near Loch Laggan.
Police looked for Mr Cooper with the help of a special search dogs unit. A Rescue 137 Sea King helicopter was launched from RAF Lossiemouth and the Cairngorm Mountain Rescue Team was immediately called out. The search went on for five days, but Mr Cooper was never found.
Now, more than six months later, and with no trace of Mr Cooper, the leader of the rescue team still can't get over his only unsolved case.
Mr Anderson said: "The whole thing has been completely vexing. We don't like unfinished business, as we like to draw a line under all of our cases. His disappearance is a complete mystery. I have been in the search-and-rescue business for 30 years and this is the first time we haven't found someone. It is a blip on an unblemished record.
"We usually find the person we are looking for, even if it takes months – but we have found absolutely no trace of Steven. It's very unusual and a real mystery.
"Sometimes people will be caught in an avalanche in February and we won't find them until the snows have melted in June," Mr Anderson went on. "But we know in this instance he wasn't avalanched. We know this because he was in the wrong vicinity; there was no snow where they found his car.
"There is a possibility that he could have gone into the loch, but we went out on canoes and there was no sign of him. Even if people do go into the water they still usually turn up, which is also what makes this such a mystery."
The RAF scanned the area with thermal imaging to pick up residual heat, but found nothing. It also used sonar in the loch, but again drew a blank.
"We generally find people not too far away, and Steven had a disease which would have prevented him from walking more than a couple of kilometres, so he couldn't have got very far," said Mr Anderson.
"If he had been in the forest, or if he had got on to the mountain, then we would have found him. I don't want to say that he is in the loch, but he didn't come to grief on land because we definitely would have found him. I am confident he is not on the mountain."
But despite all his efforts, Mr Anderson couldn't find Mr Cooper.

Answers in the case of Steven Cooper (pictured) have eluded Willie Anderson
"I'm completely perplexed," he said. "This was a massive five-day search to find a man who ultimately could not have gone very far on foot.
"Maybe he just didn't want to be found, which makes it hard when you are in the business of locating people.
"It is obviously extremely difficult for his family, who have been through a great ordeal. And, of course, we are disappointed too; disappointed that we haven't found someone we set out to find.''
Mr Anderson, who lives in Kingussie and also teaches technology at Kingussie High School, said that his team has done all it can.
"The rest is now down to the police. We are all volunteers and have full-time jobs as well, but we are never off-call. I have been on-call since 1978," he said.
Mr Cooper's mother, Margaret, does not know why her son chose to disappear in Scotland.
She told The Scotsman: "We have absolutely no idea why he went. He had been on holiday to Scotland four or five times before, and he loved the scenery up there, but I think it is just a case of Steven wanting to drive and drive.
"I don't know why he did it, but I think something must have happened. The morning he disappeared was his birthday. He had arrangements to meet his friends and family that day. Obviously he didn't show up."
Mr Cooper lived with his partner, Claire Lodge, stepson Ian, 15, and stepdaughter Zoe, 18. He also has a son, Nathan, 19, who does not live with the family.
Mr Cooper suffers from Marfan syndrome, a rare condition affecting the aorta, that prevented him from working. It left him with some difficulty walking and he sometimes walked with a stick. But, like everything else, he left it at home.
On his previous visits to Scotland, he would go camping in the hills and near Loch Ness, but he didn't take any camping gear with him, no money, no wallet and no passport – only what he was wearing.
His mother has tried everything to raise the profile of her missing son and continue the investigation.
"We visited the site where he disappeared," she said. "It was very sad for us. Such beautiful countryside, but it was awful as it was so vast and open. There was nothing there.
"We handed out posters in all the local towns, asked at hotels, stopped bikers, anyone who might have seen him. He is registered as a missing person and was on a TV documentary called Missing."
The Coopers, who raised £4,200 for the Cairngorm Mountain Rescue Team, the Search And Rescue Dog Association, and Missing People, to thank them for their efforts, also contacted the Tartan Army to help.
Don Lawson, a businessman from Inverness, e-mailed all 45,000 Tartan Army members, sending out information about Mr Cooper so they can keep an eye out for him.
All Mrs Cooper wants is information on her son.
"We just want a lead of some kind," she said. "If he is out there we just want to know that he is OK. He doesn't have to contact us, or come home; he could let the police know. We just want to know that our son is safe."
The full article contains 1163 words and appears in The Scotsman newspaper.