Recordings from a police bug in the Bournemouth home of murder accused Elliot Turner in the weeks after he allegedly killed New Zealand teenager Emily Longley in a jealous rage have been played to a jury at his trial.
Emily, 17, was found dead in Turner's bed in his parents' home in the upmarket suburb of Queens Park on May 7 last year.
The aspiring model from Auckland had been in a reportedly tumultuous relationship with Turner, 20, for about four months prior to her death.
Overnight, jurors at the Winchester Crown Court heard recorded conversations between Turner and his parents Leigh and Anita, who are accused of perverting the course of justice, Solent News Agency reported.
"A screw had basically just gone outta my brain at 10 o'clock that night, I had no conscience,'' Turner was heard saying.
"I just flipped. I went absolutely nuts I have never in my whole life got to that point. Just uncontrollability.
He added: "It's when we were arguing she punched me... I was so angry.
"I just lost it. The anger, the f***ing anger.
"I had felt this aggression for about a month. When I woke up in the morning I just feel on f***ing edge, every day.
"I never meant to harm her. I never planned it... just that argument.
"I did grab her quite hard but then I stopped. I realised I was causing her pain. She started crying, I told her to shut up.
"She sort of collapsed on the floor and I have seen it happen before. I didn't think much of it, I thought it's just usual.
"I woke up next to her and she was freezing."
His parents, who allegedly destroyed a letter containing a confession by Turner, were also heard in the recordings.
His father Leigh said: "He knew what he had done, he thought 'shall I phone an ambulance and see if I can save her?' But he didn't.
"He knew what he had done was so severe. He knew there was no point in phoning the ambulance."
Elliot's mother responded by saying, 'no I don't believe that'.
Mr Turner responded: "Yeah, but she has been dead for five of six hours. It's a terrible feeling, I want to scream, I want to run away. I want to take this weight off me."
He added: "What we did was we destroyed the vital evidence. That was a confession.
"I can't tell her about that letter I destroyed with bleach saying that he has killed her but he didn't mean to do it."
Mrs Turner: "No, he did not say that. He will just say it was self-defence."
Mr Turner: "Neet stop denying it. He f***ing strangled her."
An earlier conversation between Turner's parents revealed them talking about their son.
"Do you think we were right to destroy that," Mr Turner said.
Mrs Turner said: "Yeah."
Mr Turner added: "Because we have perverted the course of justice, we have destroyed the vital evidence in this case.
"Morally I think we were right because we're parents, but by the law we haven't.''
Emily was born in Britain but her family moved to New Zealand when she was 9 and she was raised in Auckland.
She had returned to study in Britain and lived with her grandparents in Bournemouth.
The trial, which began on April 23, is expected to last about another two and a half weeks.