A man was stabbed to death in front of his mum and sister, a court heard.

David Stunell, 22, bled to death after allegedly being knifed once in the neck by his sister's boyfriend in the street.

The attack is alleged to have happened after Mr Stunell and his mother, Carol, 51, went to his sister Hayley's flat near the Seven Dials to confront her about her relationship with Aaron Aymer, 18, who denies murder.

Mr Stunell approached Aymer, who was sitting in the front passenger seat of Hayley's car, parked in Montpelier Crescent.

It was then that he was allegedly stabbed once in the neck with a kitchen knife, Lewes Crown Court heard yesterday.

The jury was told Mr Stunell shouted out "he's stabbed me" before collapsing between two parked cars.

A doctor and an ambulance technician, both off duty, were passing by and desperately tried to save him, but he was bleeding heavily.

Mr Stunell, a carpenter, of Desmond Way, Whitehawk, was rushed to the Royal Sussex County Hospital but was pronounced dead shortly after arriving on July 28 last year.

Richard Camden Pratt QC, prosecuting, told the jury: "We say this was not an accident and this was not an act of self-defence.

"The Crown alleges that the use of the knife shows this defendant either intended to kill Mr Stunell or at the very least cause him really serious bodily harm."

Hayley, then 18 and a mother of a young child by a former boyfriend, may well have lied to her family about her relationship with Aymer, then 17, who she described as one of her "mates."

But, Mr Pratt said, the relationship had become much closer since they met three months before the fatal stabbing and he was staying at her flat in Vernon Terrace.

Mr Pratt said in the weeks leading up to the killing there had been a series of confrontations between Aymer and Hayley's former boyfriend, Michael Murray.

On the morning of the stabbing, Aymer headbutted Mr Murray when he visited Hayley's flat and punched him in the face.

Later Mr Murray bumped into Mr Stunell and told him what had happened.

A short while later Hayley drove Aymer in her Hyundai car, given to her by her brother, to a flat in Pett Close, Whitehawk, where he allegedly threatened another man with a knife, holding the blade to his neck and demanding money.

When the alleged victim, Ben Maynard, pretended to call the police Aymer allegedly ran away.

Later that day when Mr Maynard was standing outside The Winner pub, in Elm Grove, Brighton, he saw Aymer driving by. He alleges Aymer pulled out the same kitchen knife he had threatened him with earlier, and started waving it around.

A while later, Mr Stunell was told by a friend about Aymer's alleged behaviour that day.

Mr Pratt said: "It was clear David Stunell was very unhappy about the situation and his sister's involvement with this defendant.

In the evening at the New Bush pub, in Arundel Road, Brighton, Mr Stunell was again told by a friend about Aymer's actions.

Mr Pratt said Mr Stunell decided to call his mother, who suffers from MS, and ask her if she would go with him to discuss with Hayley her relationship with Aymer.

Mr Pratt said: "It did not come as a complete surprise to Carol Stunell. She had heard things about Aaron Aymer, about what he might be getting Hayley involoved in.

"David Stunell was clearly upset. He wanted to find out what was going on."

Mr Stunell and his mother arrived at Vernon Terrace at about 8pm. But at that time Hayley and Aymer had popped round the corner in her car to buy alcohol and cigarettes at a nearby off licence.

The son and his mother parked in Montpelier Crescent because they feared if Hayley saw them she might want to avoid a meeting.

When Hayley and Aymer arrived back they also parked in Montpelier Crescent. Hayley got out of her car to speak to her mother while Mr Stunell left his mother's Ford Fiesta to speak to Aymer.

Mr Pratt said: "The defendant was sitting in the front passenger seat. The door was open. David Stunell leant in towards the defendant. He put his hands on the door and on the roof.

"Within seconds he moved back shouting out 'He's stabbed me'. He was holding his neck. He took a few steps back towards his mother's car before he collapsed and ended up falling to the ground in between two parked cars."

While Mr Stunell was being helped by his mother and sister and passers-by, Aymer moved into the driver's seat and drove away. He abandoned his car outside his half-brother's in Albert Road before fleeing to Brighton Railway Station where he caught a train to his mother's home in Wapping, London.

He was arrested there the next day and told police he had been attacked without warning by Mr Stunell and had accidentally stabbed him with a knife he found in the footwell of the car. He said he panicked and drove off.

Mr Pratt said: "We say this was no accident. This was not reasonable or necessary self-defence. This was the intentional use of a knife to stab a man in the neck.

"That action caused his death. That is murder."

The trial continues.