A brother whose sister was being attacked by her violent husband stepped in and killed him with a crossbow, a court has heard.

Daniel Schofield, 29, killed plumber Roy Hanson, 50, with an arrow to the chest - but claims he was acting in self-defence.

Hanson was married to Schofield's sister Julia but they had recently separated due to his violent outbursts and she had moved in with her brother.

The court heard that Roy then turned up at the home and attacked Julia.

The defendant claimed he was fearing for his sister's life when he shot Roy with the crossbow.

Schofield denies murder and the prosecution outlined the case on the opening day of the trial at Truro Crown Court today.

Roy and Julia, of Gweek, had been married for 10 years, but had separated after years of trouble.

The court heard that Roy had been physically abusive to Julia in the past, but he had talked her into giving the failing relationship another chance on numerous occasions.

But early in 2014 Julia had started to move her possessions out of the home she shared with Roy with the help of her brother.

He became extremely agitated and drove to confront her and demanded her keys back.

At one stage Roy had got her in a headlock and began choking her.

The jury heard the defendant then became aware of the confrontation and went to fetch a crossbow he kept under his bed.

He armed himself with the weapon and went outside to threaten Roy with it.

Roy reportedly said: "Don't you f*****g dare", before marching towards the defendant.

He is then said to have pulled the trigger and a dart was fired from the crossbow which passed through Roy's chest.

It ruptured the largest chamber of his heart, and a vein which supplies blood to the heart, before passing out his back.

The defendant claimed he did not mean to shoot Roy, but instead just wanted to scare him.

He also argued that the crossbow was faulty, and had a 'hairline trigger' due to some early damage.

Paul Dunkells QC, for the prosecution, said: "He (Roy) said he wanted the keys to his house, and she decided the best thing to do was to give them to him.

"He walked off towards his van, with Julia protesting. He got in his van and started the engine.

"She reached in and took the car keys, and walked away. He followed her.

"There was a scuffle, and he got his arm around her neck.

"She told him to let go, and said she felt as thought she was choking.

"The defendant, seeing what was happening, armed himself with this crossbow, which he kept at home.

"He armed it, put an arrow in it, and went outside with the safety off.

"He shouted at Roy Hanson, and when he moved towards the defendant he fired the crossbow.

"The arrow went through his chest causing a fatal injury as it passed through his body.

"The defendant told police that he only meant to frighten Roy Hanson, and the crossbow went off by accident.

"The defendant said he knew the trigger was a hairliner, meaning more caution needed to be taken.

"The defendant did not engage the safety catch before pointing the weapon at Roy Hanson.

"The trigger must have been pulled by the defendant for it to fire."

Mr Dunkells said the prosecution's case was that the shooting was a deliberate act and he had not meant to kill him.

He said: "Roy Hanson had been mortally wounded by the arrow, which passed straight through his chest.

"When the arrow struck him it passed through his ribs, punctured one of the large chambers of his heart, and a vein which carried blood to the heart, before exiting through his back.

"The defendant said it was self defence, as Roy had been attacking his sister.

"The defendant said to his sister that he had not meant to shoot him.

"But firing the crossbow was a deliberate act by the defendant.

"A person is allowed to use reasonable force to protect himself or another but the amount of force must be proportionate.

"Roy Hanson had a reputation for being violent, on this morning Roy and Julia were struggling, and Roy Hanson moved towards the defendant.

"To fire the lethal weapon at Roy Hanson's chest was out of all proportion to the threat he posed to the defendant.

"It killed Roy Hanson, so this was unlawful, it was not lawful self defence.

"The moment he pulled the trigger the defendant meant to kill Roy Hanson, he was pointing it at his chest, which tell you his intention - that's murder."

In an interview with the police, which was read out in court, the defendant claimed that he had shot Roy Hanson in self defence.

The statement said: "He fetched the crossbow as he wanted to frighten Roy Hanson.

"He didn't put on the safety catch in panic.

"He shouted at Roy Hanson to let his sister go, then he sort of flinched and the bow went off.

"He said Roy Hanson was known to be a violent man, and he generally feared for the life of his sister, and everyone there.

"The look of aggression on Roy Hanson's face made him think he meant to hurt his sister.

"He said that if it was not cocked Roy Hanson would not be afraid.

"Roy Hanson's hands were round his sister's neck, the defendant told the police at first the bow was pointed at the ground.

"He thought he had missed as Roy Hanson kept going, then he struck Roy Hanson with the crossbow, before running away."

Quoting the defendant directly, the statement continued: "I probably thought 'stop it'. All I can recall was that there wasn't any time to think.

"It was an instant instinctive move, it was do or die."

Schofield, from St Keverne, Cornwall, but currently living in Exeter, Devon, had previously pleaded not guilty to two counts, one of murder and one of manslaughter caused by gross negligence.

The trial, heard by Judge Graham Cottle QC at Truro Crown Court, continues.