VIDEO: Timeline Of Karen Buckley's Murder

Alexander Pacteau killed Karen Buckley within 20 minutes of meeting her outside a Glasgow nightclub and spent the following two days trying to dispose of her body as police mounted a major search for her.

Pacteau had entered the club just minutes before Miss Buckley and her friends at around 11.45pm on April 11. He left the club at around 1am alone, telling a steward he was going to get something from his car which was parked around 100 metres away.

A couple of minutes later, Miss Buckley left the club, intending to go home.

She crossed Dumbarton Road and ended up near where Pacteau was standing using his mobile phone. It is not known what transpired between them while there but CCTV showed they walked together towards Pacteau's car.

Further footage then showed his car driving towards the city centre in the direction of Miss Buckley's flat before entering Kelvin Way.

The car was parked there for 12 minutes 46 seconds, during which time Pacteau grabbed her by the neck and hit her repeatedly with a spanner.

She was dead when the car left Kelvin Way at 1.18am. Footage showed his car heading towards Dawsholm Park, where Miss Buckley's handbag was later discovered. It left the area at just after 2am and Pacteau drove to his nearby flat on Dorchester Avenue.

He took her body wrapped in a sheet into his shared flat, locking his bedroom door.

At around 8am on the Sunday, he used his mobile phone to look up the properties of a chemical called sodium hydroxide, or caustic soda - a high alkaline corrosive substance.

He then travelled to a B&Q store where he bought caustic soda, masks and gloves. He also went to a Poundstretcher store near his flat and bought more of the chemical.

He texted his flatmate to make sure he was out for the day, then returned to the flat and moved Miss Buckley's body into the bath.

Pacteau was found cleaning the hall when his flatmate returned home at around 8pm. He had moved her body back into his locked bedroom wrapped in a duvet.

The following day he left his home at around 5am and went to a nearby canal where he threw the bloodstained spanner into the water.

He then drove to Tesco on Maryhill Road to buy cleaning materials, asking a member of staff to recommend a product for removing blood from a mattress.

He made his first journey to High Craigton Farm, an area familiar to him from a previous job selling fireworks which were kept in a storage unit there.

He stopped off at Tesco in Milngavie at 6.30am and bought white spirit and a lighter to burn clothing.

The 21-year-old then returned to his flat where he used his mobile phone to call a packaging company and ordered a blue 220 litre barrel.

Pacteau collected the barrel from an industrial estate on the other side of the city at 9am before driving to a shop to buy more caustic soda and drain unblocking fluid.

When he arrived back home, he put Miss Buckley's body in the barrel.

He drove to Asda in Bearsden and bought another lighter and lighter fluid. CCTV footage taken at around 10.30am showed his car in the car park with a mattress in the back.

He then drove to the farm and burned the mattress and cleaning items at the same spot as before.

At 11.19am, images were recorded of his car driving in the opposite direction from the farm, heading home. He poured more chemicals into the barrel before sealing it. He was seen by a witness struggling to put a large blue barrel in his car outside his flat at around 2pm.

After setting off from home, he stopped at the same supermarket and bought two padlocks and more white spirit.

His car is then seen driving towards the farm at 2.35pm. Images showed the barrel in the back of his car.

He arranged to rent a storage unit there and used one of the padlocks to secure the lid of the barrel. He then covered it with a bed sheet and weighted it down with a paper shredder and bike wheel.

Pacteau used the other padlock to secure the door of the storage unit.

He visited a car valet on his way home and while waiting for the Ford Focus to be cleaned, Pacteau used his phone to create an advert to sell his car.

At 5pm, he drove home where police knocked on his door around an hour later.

As he opened the door to officers, Pacteau said: I was just coming to see you.''

He gave detectives a version of events which said he met Miss Buckley outside the club and they both went back to his flat where they had consensual sex, but she had fallen and injured herself on the bed frame.

He told them he had burned the mattress and clothes on a forest road because he was aware he was the last person to see her alive.

It was all lies and police inquiries soon led to High Craigton Farm where they found the blue plastic barrel containing Miss Buckley's body.

Defence QC John Scullion told the court Pacteau accepted ''full responsibility'' for his actions but that he can offer no "rational explanation''.

Speaking outside court, Detective Superintendent Jim Kerr said there was no connection between Pacteau and Miss Buckley and that it had been a "random attack''.

He said: "It could have happened to any female that night, we can't see anything from our investigation that would have predicted what he did on the night in question.

"We have no information as to why she got in the car, all we know is she left that nightclub to go home to the city centre and he headed off in the car in that direction.''

Asked if Pacteau was waiting outside to prey on a woman, Mr Kerr said: "I think there was premeditated plan that night to find some victim, yes I do.

"He has been calculated and callous, you can see that from his actions after the event and what he did.

"They're complete strangers and he's made a concerted effort to destroy any evidence as to Karen's whereabouts. He had the opportunity at various times during this investigation to tell us exactly where she was and he didn't do that either.''

Judge Lady Rae told Pacteau: "This crime is a very shocking and disturbing case. You killed a young woman who was a stranger to you in what appears to be a motiveless, senseless, brutal attack."

She added: "What you did after her killing, including telling the police a tissue of lies - some of which went into the public domain - would I have no doubt caused the family increased distress. All of that displays the actions of a man who is callous and calculated.''