A teenager was acting in self-defence to protect himself and his friends when he lashed out with his “zombie knife” at a house party, fatally wounding a 16-year-old boy, a court has heard.

The defendant will claim he stabbed Mikey Roynon in the neck after being confronted by a group of armed teenagers, Bristol Crown Court was told.

He is one of three 16-year-olds on trial accused of Mikey’s murder. A court heard earlier that the youngsters travelled by bus from Devizes to the venue in Bath.

Christopher Quinlan KC, prosecuting, told the jury the teenager had submitted a document to the court, setting out his version of events.

“We anticipate he will say he had a knife,” Mr Quinlan said. "He stabbed Mikey in the neck with it and therefore caused the injuries that led to his death.

“What we understand his case to be is that he was defending himself and/or others. He will say Mikey struck out with a knife first at (Boy B) and then him.

“To defend himself and others he struck out with his knife, stabbing Mikey in the neck.”

The jury has been told that trouble flared at the 16th birthday, which was being held at a house in Eastfield Avenue in the Weston area of Bath on the evening of June 10 last year.

Around 50 people were at the party when Mikey was stabbed in the garden and collapsed and died a short time later.

The defendants left the scene and later disposed of their weapons, two of which were recovered by police.

The first, which was found in a drain, was nearly 10in (25cm) long and scientists found Mikey’s blood on the blade. Boy A’s DNA was “well represented” on the handle, which Mr Quinlan suggested was because he had used it to stab him.

The second knife, which was recovered from underneath a hedge, was 7in (18cm) long and had traces of Mikey’s airborne blood on the blade – meaning it was close to the victim when he was stabbed.

Mr Quinlan said Boy C’s DNA was among a mixed profile of DNA recovered from the knife and its sheath.

“We say he had possession of that knife, we say it was his knife,” he said. "If blood was on the blade it must have been out of its cover at the time it got there.

Two of the defendants, Boy A and Boy B, were arrested soon afterwards, while Boy C was arrested some months later.

Boy A initially told police in a prepared statement: “I deny this allegation. I accept I was at the house party, and I accept I attended with a group of friends who were invited.

“I deny having a knife with me and I deny stabbing anyone. I have nothing further to say.”

Boy B told police in his prepared statement: “I accept I was at the party on June 10. I didn’t see Mikey get stabbed. Mikey didn’t swing a knife at me.

“I didn’t hold a knife at any time. I deny involvement in Mikey’s death. I have nothing further to say at this time.”

In his prepared statement, Boy C said he had first been interviewed by police as a witness in the days after Mikey’s death and then was arrested the following October.

“At the time I was spoken to as a witness I was really scared and it was soon after the murder,” he said.

“The party on June 10 was the first party I had been to. Someone had been murdered and it was a frightening experience. I knew my friend had been arrested.”

Boy C said that when he made his witness statement he did not tell police he had made a phone call to his mother or that he had handled a knife at the party.

“When I was at the party, I was talking to someone and I saw he had a Rambo knife. He handed it to me and I touched it and I took it out of the sheath,” he said.

“I didn’t tell the police I had touched a knife because I didn’t want to get into trouble.”

Mr Quinlan suggested Boy C was using his prepared statement to “lay the ground” for an explanation as to how he was linked forensically to a knife.

The defendants, who cannot be identified for legal reasons, deny murder.

Boy A and Boy B have pleaded guilty to possessing a bladed article, which Boy C denies.

The trial continues.