McDonald will be sentenced at the High Court in Edinburgh in October
A man has admitted murdering his ex-girlfriend in a fit of jealousy during a fight in Ayrshire.
The High Court in Edinburgh heard how Stuart McDonald, 21, stabbed 18-year-old Laura Thomson in the neck after alleged taunts from her over other men.
The attack, at his twin brother's home in Ayr, on 1 June, happened a short time after he had assaulted her.
McDonald, who has a 17-month old daughter with the dead teenager, will be sentenced next month.
The court heard how McDonald and Ms Thomson, both from Ayr, split up in February but still occasionally saw each other.
The night before the attack he came into a bar where she was drinking and told a friend that her was "going to do her in".
The following evening McDonald assaulted Ms Thomson during an argument in the grounds of a local church.
His twin brother, Jamie, took her back to his house but McDonald followed them.
He was thought to have left his brother's house when others there heard screaming from the hall.
They saw that Laura was hurt and that McDonald had a knife in his hand.
Doctors at Ayr Hospital later found that the fatal wound had severed vital blood vessels in her neck.
She had other stab wounds to her face and cuts to her hands where she had tried to fend off the blade.
Lord Kinclaven called for background reports and remanded McDonald in custody for sentencing next month.