Nicola Anderson: Nothing to connect pair but a painful succession of ‘if onlys’
'Our deepest fear is not that we are inadequate. Our deepest fear is that we are more powerful beyond measure," he wrote. "It is our light, not our darkness, that most frightens us."
As a teenager, Alexander Pacteau plundered this quote by American spiritual teacher Marianne Williamson for his Bebo social media account.
But by the age of 21, the young man whom two psychiatrists deemed 'sane' had apparently become obsessed with the elements of power and fear, committing a murder so savage and sickening that it could barely be imagined, let alone understood.
Two years before Karen's brutal murder, while up on charges of sexual assault, Pacteau brazened it out, hotly claiming he would "rather be tried with murder than rape".
A jury found him not guilty, but Pacteau's comment shows how his mind was operating.
Most heartbreaking of all was how Karen's father, John, told how Pacteau had robbed them of Karen in death as well as in life.
They had been unable to hold her close or even see her.
Pacteau had effectively rendered her remains a bio-hazard.
The only thing that connected the pair was a disturbing and painful succession of 'if onlys'.
If Pacteau's taxi had only turned up on time, because the delay made him think of taking his own car. If Karen and her friends had not thought of going to The Sanctuary that night. If Karen had not left the club early. If her friends had only gone with her. And, most haunting of all, if charitable, kindly, Karen had not deemed Pacteau to be unthreatening enough to warrant getting into a stranger's car.
"I can't get that girl out of my head," said an elderly fruitseller, pausing as she bagged oranges at her stall on Argyle street in Glasgow's city centre, adding gently: "I pray for her every day."
That Karen's death occurred in the comparatively salubrious, mostly safe West End, following a night out at a sophisticated club with table service made it utterly different to the usual 'gangland' killings.
The Sanctuary is a popular destination for nurses, in particular, because it's right across the road from the Western Infirmary Hospital.
Retracing the final journey of Karen, we went to see the hospital - a big barracks of a building, painted dark grey - but at night, the area is busy, bustling and feels safe.
She left the club at 1am and crossed the road close to where Pacteau was standing and the pair were picked up on CCTV, walking to where his car was parked, 100m from the nightclub entrance.
They drove east and Pacteau veered off the main road to Kelvin Way, which cuts through Kelvingrove Park and Glasgow University with its tree-lined boulevard close to the river Kelvin. By day, it is pleasant and popular with dog-walkers, but by night it is known for its seedy atmosphere.
After 1am, there would have been few people, if anyone at all, hanging around.
It took just 12 minutes and 46 seconds for Pacteau to snuff out the life of the trained nurse who had a special talent for caring for the elderly and who had "a smile to lift a thousand frowns". He struck her 13 times with the spanner that had conveniently lain in the passenger footwell of his silver Ford Focus.
After disposing of Karen's handbag in a bin close to Dawsholm Park, Pacteau simply went home, easily lugging Karen's tiny body up the 14 steps to the flat complex. She was just five foot three inches tall and weighed eight-and-a-half stone, so it would not have been difficult for his heavy, hulking frame.
Dorchester Avenue is a grim and cheerless spot - a bleak residential street of mainly old stone apartment buildings.
After getting an astonishing eight hours sleep next to Karen's body, which Pacteau had wrapped up in a duvet, he got up the next morning, Googled corrosives, and headed off to B&Q to buy six litres of caustic soda, masks and gloves.
Karen's body remained in the flat on Dorchester Avenue, Pacteau having secured his bedrom door with a padlock.
We hit the buzzer for one of Pacteau's former neighbours - after explaining why we were there, he hung up flatly without comment.
We travelled out of Glasgow a short distance across the Western Highlands to High Craigton Farm, which rears organic sheep and goats and where the 200-year-old whitewashed farmhouse formerly operated as a B&B.
The area is scenic and close to Loch Lomond, but you would have to know where you were going in order to find this place. And Pacteau did.
There are around five doors to the outhouses, well-secured with padlocks.
Farmer Adam Fisken tells us wearily that they have been inundated by media in the previous week, while his wife waves us off with a "no comment".
It was here that Karen Buckley's remains were mercilessly stashed, the nurse curled up in a foetal position in a blue barrel of caustic soda.
But after three days, she was discovered. Two weeks later, Karen was afforded the dignity of the funeral Pacteau never intended her to have, at home in Mourneabbey.