Stewart Blackburn denies murdering 17-year-old Jessica McCagh
A murder trial has heard the accused told police his girlfriend went on fire after he "slapped" a jerry can of petrol at her, covering her in fuel.
Stewart Blackburn, 18, said the petrol then burst into flames as he smoked a cannabis cigarette and "burning bits" fell off the end of the joint.
His girlfriend Jessica McCagh, 17, received 85% burns and died within hours in Ninewellls Hospital, Dundee.
He denies murdering Miss McCagh in Arbroath, Angus, on 25 April.
The High Court in Livingston heard he made the admission in the third of three interviews he gave to officers at Arbroath police station after the fire at his flat.
The reference to slapping the petrol can came on the sixth day of his trial - Mr Blackburn denies murder, but has tendered a plea of guilty to causing death by culpable homicide, by throwing petrol around which then ignited.
The court heard the unemployed teenager kept a mini-motorcycle in his flat, and it was a half-full can of fuel intended for the bike that caused the blaze.
In an interview taped and played to the court, jurors saw and heard Mr Blackburn describe the incident to investigating officer DC Gary Simpson.
He said Jessica had revealed that day she wanted to get engaged to him.
But he said they had an argument in his flat in Bloomfield Road, Arbroath, after they returned from a party that night.
Jessica McCagh died of her injuries at Ninewells Hospital
He admitted that on the way back he had hit her twice, and in the flat, he said he punched and smashed a mirror.
Then he told DC Simpson and another officer: "I'm going to tell you the truth. I'm going to jail for this anyway. I threw the jerry can at her when we first came in the house. And she went to bed. I threw the jerry can at her. There's the truth. I did."
DC Simpson asked: "Was the can open?"
Mr Blackburn replied: "Yeah."
DC Simpson asked: "Did she get covered in petrol?"
Mr Blackburn: "Yeah."
He went on: "I slapped the jerry can at her just to annoy her like. I didn't want this to happen. You know I didn't."
Mr Blackburn said he later suggested Jessica should go to the bathroom and get the petrol off. He said the smell of the petrol in the bedroom was so bad that he was going to take all the covers off the bed and turn the mattress over.
He said he then went back into the bedroom with the joint and lit it.
He said: "As soon as I took one toke it just went shtttt.
"It wasn't her that went up, it was the bed that went up first."
He said that when the fire broke out, he grabbed Jessica by the ankles, pulled her out of the bedroom, and threw water over her.
He said: "I didn't want to kill her."
At the end of the interview, jurors heard Mr Blackburn was told he was going to be charged with murder.
He responded: "That's my life gone in jail."
He also said: "I wonder whether I can go to her funeral or not?"
The trial before Lord Bracadale continues.