Crown lawyers have told a British court that a man accused of killing New Zealand teenager Emily Longley thought she was being unfaithful to him and strangled her after an argument.
Elliot Turner, 20, is on trial at Winchester Crown Court accused of the murder of Ms Longley, whose body was found in his bed, in Bournemouth, in May last year.
He denies murder and perverting the course of justice.
The Crown alleges Mr Turner strangled the 17-year-old after an argument at his parent's home.
Prosecutor Timothy Mousley QC said Elliot Turner was aggressive, violent and controlling towards Ms Longley during their short relationship.
The court heard that Mr Turner told friends that he would kill her if she was unfaithful.
Mr Turner's parents, Leigh, 54, and Anita, 51, have pleaded not guilty to perverting the course of justice for allegedly removing evidence from the scene and destroying a confession note.
Emily Longley's New Zealand-based parents have been in court for the trial, which is set down for one month.