AN ALLEGED killer got engaged to her boyfriend hours after he stabbed her ex-partner to death in their flat, a court heard.

Isabella Gossling, who denies the murder of "vulnerable" Phillip Nicholson, agreed to marry Richard Moors as they fled Bournemouth, prosecutors have alleged.

The proposal was captured on an audio recording device habitually used by Gossling as the two travelled to Weymouth by bus, the court heard.

It is claimed that the proposal took place shortly after Gossling and Moors "lured" Mr Nicholson to their flat in Sea Road on the pretext of meeting a girl before he was knifed to death.

Moors, 26, has admitted the murder of the 22-year-old, who was found at the property shortly after midday on Tuesday, May 26.

He had suffered wounds to his neck, one of which was approximately seven centimetres in depth and severed his carotid artery.

Prosecutors allege that a knife with a serrated edge was placed underneath Mr Nicholson's hand to make it appear as if he had committed suicide.

Nigel Lickley QC, prosecuting at Winchester Crown Court, said Mr Nicholson "was not killed quickly" as the result of "some random act".

"Whatever the reason, he was subject to severe violence that day," Mr Lickley said.

"He was removed as a person because he was some sort of hindrance to the lives of the defendants."

The prosecutor said Mr Nicholson "was subject to a terrible ordeal".

"I don't use this word lightly - [it was] verging on torture," he said.

"He was tormented, frightened and killed and that was deliberate."

A consultant psychiatrist who gave evidence at the court during Tuesday morning said Mr Nicholson had an IQ of 62, and described him as "shy" and "quiet".

Dr Anthony Mason, who had worked with Mr Nicholson since 2009, said he had "difficulty expressing feelings," adding that he "tended to say what he thought others wanted to hear".

Despite this, he "enjoyed the company of others".

Mr Nicholson had also spoken to his community learning disability nurse of feeling "lonely" and wishing for a relationship, it was heard.

And an independent domestic violence advisor called in following concerns raised over Mr Nicholson's relationship with former partner Gossling said he was at "very high" risk of "emotional, mental, financial and sexual abuse".

It was alleged that the advisor spoke with Mr Nicholson in 2014 after being contacted by social services.

The trial of Gossling, 20, of Sea Road in Boscombe, continues.