The man who murdered Karen Buckley by hitting her at least 12 times with a spanner before hiding her body in a barrel of chemicals has been branded "truly evil" by the Irish student's father.
Alexander Pacteau, 21, pleaded guilty to the post-graduate student's "senseless and brutal" murder at the High Court in Glasgow.
The remains of 24-year-old Miss Buckley were found in a barrel on a farm on the outskirts of Glasgow four days after she disappeared from a nightclub in the city's west end in April.
Outside the court, her father John Buckley, who had travelled from Cork for the hearing with his wife Marian, said: "It is every parent's worst nightmare. There are no words to describe what we went through.
"Being told Karen was brutally murdered and having to phone our three sons and tell them Karen was dead was one of the hardest things we've had to do.
"What a waste of a young life, it all seemed unreal, we were devastated.
"All Karen was doing that night was making her way home when she was randomly targeted by and murdered by a cowardly, vicious criminal.
"He is truly evil and we hope he spends the rest of his life behind bars."
Pacteau, from Glasgow, faces a mandatory life term when he is sentenced on September 8.
The killer has a previous conviction for printing counterfeit money and it has emerged that he stood trial at the High Court in Paisley in 2013 accused of attempting to rape a woman in a Glasgow lane. He was found not guilty of the charge.
Today, the court heard how Pacteau met Miss Buckley outside The Sanctuary nightclub in the city's west end in the early hours of the morning on April 12.
CCTV footage captured them walking along Dumbarton Road and Pacteau then drove with her in his car to nearby Kelvin Way.
The car was parked on the street for 12 minutes, during which time Pacteau, who describes himself as a ''self-employed sales consultant'', attacked and murdered her by grabbing her neck and delivering 12 or 13 blows with the spanner.
Miss Buckley suffered injuries to her arm as she tried to defend herself.
Her family were in court as Lord Advocate Frank Mulholland QC, prosecuting, told how Pacteau attempted to dispose of her body.
He embarked on a journey to various stores to buy quantities of caustic soda before placing her body in the bath at his flat after making sure his flatmate was out for the day.
Pacteau made trips to High Craigton Farm where he burned a mattress, clothes and cleaning materials before buying a barrel, placing Miss Buckley's body inside and locking it in a storage unit he had rented.
Meanwhile, a major search was launched for Miss Buckley after she was reported missing from the flat she shared with friends.
When police officers knocked on Pacteau's door after he was identified on the CCTV footage, he answered saying "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."