A jealous boyfriend murdered his girlfriend by stabbing her in the face after learning she planned to leave him, a court has heard.

Pawel Sroka, 34, today admitted the manslaughter of Joanna Trojniak, who was found with multiple knife wounds in Meadvale Road on March 23 hours after telling a friend she was going to break up with him.

After killing the 29-year-old in the couple's terraced house he stabbed himself in the chest before calling 999, the Old Bailey heard this morning.

Ms Trojniak was pronounced dead in her home after being found with knife wounds to the chest, hand and face just after 9pm.

Police arrested Sroka after officers found him suffering knife wounds in nearby Gordon Crescent at about 10.35pm on the same night. 

He denies murder and is still facing a trial as prosecutors have not accepted the lesser charge of manslaughter.

Opening the trial at the Old Bailey this morning, prosecutor David Jeremy told the jury Sroka had knifed Ms Trojniak at least six times after she returned home from work at Nando's in Colliers Wood.

He then stabbed himself in the chest before calling 999, the court heard.

Mr Jeremy told the jury that week before her death Ms Trojniak confided in her manager about her plans to "run away" from Sroka, who she feared would kill her if she told him she was leaving.

Her boss asked why she "didn't just leave," to which the court heard Ms Trojniak replied: "Are you crazy? He will kill me."

Mr Jeremy told the jury: "She said the same to other friends, and of course she turned out to be correct. That's exactly what he did."

Ms Trojniak told colleagues Sroka had become "aggressive" and locked her in a room when she tried to break up with him previously, the court heard.

In the weeks leading before her death Ms Trojniak had "become close" with a colleague at Nando's, Paulius Simas.

As part of her plan to leave her relationship she tried to "cover her tracks" by redirecting her post to a friend's house, Mr Jeremy said.

But confirmation of the change was sent to her house and intercepted by Sroka on March 23, when he sent a barrage of "enraged" texts to Ms Trojniak.

Later that day told Mr Simas in a text "I’m going home now, I need to talk, no other choice.

"Don’t know what’s going to happen… and how it finish today."

Little more than an hour later, Ms Trojniak was dead.

Police and paramedics found her lying in the foetal position in the couple's living room. 

Her face had been slashed and she had suffered multiple stab wounds to her chest, as well as another that penetrated her left hand.

Blood was found splattered on the living room ceiling and sofa, Mr Jeremy said, while a large red knife discovered in the kitchen was covered in blood that matched that of Ms Trojniak and Sroka.

When Stroka called 999 he told the operator "my girlfriend has been stabbed... stabbed with a knife," but provided no further details and did not wait for emergency services to arrive, the jury was told.

The court heard he told a passer-by he had been stabbed after being discovered "slumped in the driver's seat, pale and sweating" in his Vauxhall Vectra in Gordon Crescent.

He was arrested and taken to St George's Hospital for treatment.

Mr Jeremy told the court Sroka initially admitted killing his girlfriend, refusing legal advice and telling police: "I've just done it, right."

Later he remained silent with a blanket over his head as police tried to interview him in his cell.

The prosecutor told the jury Sroka was likely to offer a defence of "loss of control" in relation the murder charge, but added: "Anyone who stabbed their girlfriend to death could in the loosest sense be said to have lost control, because it's not something any sane person would do.

"[It is] not designed to be a defence for any man who does not control themselves to kill under emotional pressure.

"Mr Sroka would not be the first or last man upset by the prospect of his girlfriend leaving him."

Mr Jeremy told the jury that Mr Sroka had been "fuelled by a murderous hate, stabbing the woman that was leaving him in the middle of the face". 

He added: "It's clear she was in fear of the defendant and what he might do if she left him.

"It's clear that confronting him was the last thing she wanted to do. She wanted to get away and avoid the confrontation."

A post-mortem examination at Croydon mortuary on March 24 concluded Ms Trojniak died of a stab wound to the chest.

Sroka denies murder.

Wearing a blue polo shirt, he showed no emotion as he watched proceedings from the dock this morning. 

The trial continues.