A man was "regularly" threatened with death by the person he is accused of murdering, a court heard today.

Andrew Boag, 35, made the threats against Stephen Lowe, and his girlfriend Tereasina Leighton, because he accused them of “grassing” him to the police following an assault, St Albans Crown Court was told.

Mr Boag died following an incident in Garsmouth Way, Watford, on Friday, July 25, 2008. Lowe has pleaded not guilty to murder.

In the witness stand, Ms Leighton said she had known Lowe, whose nickname is Frosty, for more than 17 years and was in a relationship with him at the time of Mr Boag's death.

She had also known Mr Boag for between four and five years, the court heard.

She told the court Mr Boag kept calling Lowe “a grass”, because when she was assaulted by Mr Boag, Lowe encouraged her to tell the police.

She said: “When I was assaulted by Andy Boag I asked for Frosty's advice about whether to press charges. A lot of people were bullying me, telling me not to.”

The assault happened after Mr Boag had stolen Ms Leighton's daughter's mobile phone, the court heard.

“He poured a glass of beer over my head, pulled me by my ponytail to the floor and dragged me to my flat (from a friend's home next door). He kicked the front door off and kicked me in the mouth,” she said.

As a result, Ms Leighton lost her two front teeth and suffered severe bruising to her face – photos of which were shown to the jury at St Albans Crown Court.

Mr Boag was found guilty of ABH, given a 12-month probation order and told to pay £150 to Ms Leighton, money she said she never received.

Mr Boag breached his probation, however, and went to prison.

It was shortly after he was released from jail, approximately five months before his death, that he discovered “Frosty” had supported Ms Leighton's decision to report the assault, the jury heard.

“Within five or ten minutes, he called Frosty and called him a grass down the phone,” she said. “He made threatening phone calls to me or Frosty. He phoned me on one occasion threatening me with a gun. He threatened to shoot me, my P*** kid and my seven-foot n***** boyfriend.”

Ms Leighton told the court that on the day of Mr Boag's death, she hadn't spoken to “Frosty” but knew he had tried to contact her because she had some missed calls on her mobile phone.

She said she didn't know “Frosty” had returned to Watford, and she didn't answer a knock on her door at around 8.30pm on Friday, July 25, 2008.

The court heard that Ms Leighton was later told by a neighbour that Mr Boag had “p*ssed” on her front door that evening, and then at 10pm her mother called to tell her “Frosty” and Mr Boag had had a fight.

Ms Leighton said she then received a phone call from Lowe, who told her he had knocked at her door but with no answer, he went to deliver a teddy bear to his son.

Then, the court heard, as Lowe got out of a van in Garsmouth Way, he was approached by Mr Boag, who was “verballing” at him.

Ms Leighton told the court that Lowe hadn't told him the details of the “fight”, only that Mr Boag had shouted: “You f****** *****, I'm going to kill you.”

The couple spoke again on Saturday, July 26. Ms Leighton said: “He was shaken more than anything. He said he didn't mean to kill him.”

She said during one conversation, Lowe told her Mr Boag was “still alive” when he left the scene.

Then on Monday, July 28, Lowe handed himself in at Watford Police Station.

In cross-examination by Ann Cotcher, QC, representing Lowe, Ms Leighton said “Frosty” was working outside Watford “to get away from Andy Boag”.

The jury also heard more examples of the threats Mr Boag had “regularly” made toward Ms Leighton and Lowe.

Ms Leighton said: “Andy said he wanted to kill him, that he was going to shoot him. He went out and bought a gun especially to kill Frosty.

“He wanted a reputation where everyone would fear him. He wasn't far from it.

“He threatened to knock the rest of my teeth out after he found out I spoke to Frosty.

“I took his threats seriously because other people said he had a gun and they had seen it.”

The witness added that Lowe was “swarmed with guilt” after Mr Boag's death.

She said: “Frosty was in tears, he couldn't believe he had taken someone's life.”

Earlier this morning, two more witnesses told the court they had heard screams of “Get off him” and “You're going to kill him” on the night of Mr Boag's death.

One witness heard shouting from his flat on the evening of July 25, 2008, and could see a fight taking place on the front seat of a taxi parked in Garsmouth Way, in the Meriden estate.

He told St Albans Crown Court: “I saw a white male with both legs out of the door, sitting on the front passenger seat. The other man, a black man, was holding him in and I could see arms moving, as in punching movements. The punching movements were coming from the black man.”

The witness said a young girl standing by the dark Mercedes car was shouting.

“She was saying things like: 'Get off him, get off him, you're going to kill him',” he told the court.

The witness added: “I remember the black man dropping something on the floor. It did sound metal but I couldn't tell what it was.”

The jury also heard that as the “black male” walked away from the scene, he turned back to the girl.

The witness told the court: “The girl was saying: 'You killed him, you f****** killed him.' The black man said: 'I don't f****** care.'”

A second witness said she remembered seeing a “black male crouched down or kneeling down”, who was punching a white male on the front passenger seat of a taxi, the court heard.

As the punching continued, the jury heard that the “white man” getting further into the back of the car.

After watching the incident for several minutes, the witness telephoned 999 and the transcript of her telephone call was read out in court by prosecutor Anne Evans.

The resident explained to the emergency operator that a “person is being beaten up in a car”. She said the “white man” was trying to get out of the car but the “black man” was pushing him back in.

She then described what was being shouted at the scene, to the operator.

“They are saying: 'It's Frosty, get off him. Don't kill him Frosty.' They were calling him Frosty. All the people round the car were telling him to get off him. People around the car were shouting: 'Get off him Frosty.'”

The witness then told Ms Evans she “wouldn't say the white man was punching back or fighting. He [the black male] was using very severe force”.

Stephen Lowe, of Breakspeare Close, Watford, has pleaded not guilty to the murder of Andrew Boag, in Garsmouth Way, Watford, on Friday, July 25, 2008.

He has also pleaded not guilty to an alternative count of manslaughter.

The trial continues.