A man who ran from the witness box, leapt into the dock and attacked a murder accused during a high court trial has been jailed for more than three years.

John Quinn, 28, also threatened another witness during a trial at the High Court in Glasgow in April.

He claimed he lost his temper after murder accused Craig Simpson smirked at him.

Quinn launched an attack on Mr Simpson, punching and kicking him and stamping on his head as he sat flanked by two G4S officers. It took four police officers to restrain him.

Earlier that day he had threatened Mr Simpson's partner, Debbi Clark, in a court corridor.

Advocate depute Bernard Ablett, prosecuting, said: "Craig Simpson faced an allegation that he had murdered John Quinn's cousin, Margaret Quinn, and a second allegation that he had attempted to murder Mr Quinn.

"As he walked towards the witness box Mr Quinn glared at Craig Simpson, who was sitting in the dock.

"He entered the witness box and Judge Nigel Morrison administered the oath and then warned Mr Quinn about incriminating himself.

"The accused then placed his jacket down behind him, ran from the witness box, hurdled over the front of the dock and assaulted Craig Simpson, repeatedly punching him on the head and kicking and stamping on his lower body.

"The two G4S officers on either side of Craig Simpson were unable to prevent the accused's attack.

"They, and four police officers restrained the accused, who was escorted to the cell area."

Mr Simpson suffered a graze at the top of his head, a graze on the bridge of his nose and swelling to his forehead.

The High Court in Glasgow was told that after Quinn's attack on Mr Simpson that trial had to be abandoned and restarted the next day with a different jury.

The murder and attempted murder charges against Mr Simpson were found not proven.

On Monday, at the same court, judge Lady Rae told Quinn: "You have pleaded guilty to two serious charges during a murder trial.

"You threatened a female witness who had just given evidence, you then entered the courtroom left the witness box and assaulted the accused in full view of the judge and jury.

"It took four police officers to restrain you. You can't take the law into your own hands."

Quinn was jailed for a total of three years and four months.

Solicitor advocate Ann Ogg, defending, said: "This was the first time he had seen Mr Simpson since the alleged murder.

"He looked over towards the dock and Mr Simpson smirked at him. It was like a red rag to a bull."