A war veteran throttled his mother shouting "you're dead" years before he killed a Britain's Got Talent finalist, a court has heard.

Desmond Sylva, 41, is on trial at the Old Bailey for repeatedly stabbing his girlfriend Simonne Kerr, 31, in the face and neck on August 15 last year.

The former soldier has admitted the nurse's manslaughter but denied murder, citing depression.

Jurors heard how on March 30 2010, Sylva was charged with causing grievous bodily harm with intent to his mother Patricia King.

But days later, the charge was dropped after Ms King withdrew the allegation, saying she was not willing to give evidence against her son, jurors heard.

In a witness statement read to the court, Ms King had told how her son had been staying with her when he became "more and more agitated" constantly touching his hair and shaking.

She had previously seen him behave like this when he was in hospital, according to her account.

She recalled asking him whether his then wife Pinar Sylva and their baby had gone back to Germany and he replied "yes" in a very hostile manner.

She told police he had been upset about the prospect of his wife not returning from Germany with their child.

While she was reading a text message, Sylva grabbed his mother round the neck saying "help help", the court heard.

Ms King responded: "Sparrow, it's me your mother" and he allegedly replied: "Mother you're dead."

He allegedly put his arm around her neck and put his fingers down her throat to stop her calling for help.

He forced her to the ground and straddled her as he continued to say "mother you're dead", it was claimed.

Ms King told police how he tightened his grip on her throat, making her "scared for her life".

Prosecutor Louise Oakley told jurors: "Ms King told police the last thing she recalled was blood coming from her mouth before she passed out.

"In her opinion, Desmond knew exactly what he was doing.

"When Ms King regained consciousness, Desmond had left the address and she climbed out of a window and summoned the assistance of a neighbour and police."

She was taken to hospital with swelling to her throat and tongue and carpet burns.

Meanwhile, Sylva had travelled to Germany but returned to Britain two days later and made no comment when interviewed by police.

Days later, Ms King made a further statement withdrawing her allegation, saying her son had been in an "extremely depressive state" with "suicidal and aggressive thoughts".

The prosecution was forced to drop the charges after a judge at Woolwich Crown Court refused to agree to a witness summons.

At the time of the alleged incident, Sylva had been an infantry soldier in the Royal Regiment of Fusiliers.

Over 10 years in the Army, he had served in Iraq and Kosovo before he was discharged in 2012 on medical grounds.

He was diagnosed with post traumatic stress disorder, bipolar disorder and depression and was working as a security guard at the time of the killing in his flat in Clapham.