A 21-year-old man who stabbed his younger brother to death with a samurai sword has been jailed for life.
Lincoln Crown Court heard Julian Mayfield-Sparks stabbed his brother Corin Mayfield-Sparks, 18, after a row over noise on 1 June 2007.
Mayfield-Sparks of Bridge End Road, Grantham, Lincolnshire, denied murder, claiming he was acting in self-defence but was found guilty of the charge.
Judge John Milmo said he should serve a minimum of 12 years in prison.
He said the trial had been "one of the most traumatic cases" he had ever dealt with.
The court heard mother Deanna Mayfield-Sparks stood between them as the 18-year-old suffered the fatal wound.
The blow from the 2ft (61cm) weapon cut into Corin's aorta, leaving him to bleed to death in a matter of minutes.
His brother later told police he was simply holding the sword in his hand when the teenager came towards him and accidentally impaled himself.
The jury was told Julian had been watching a film on his laptop with friends before the incident.
Corin had complained about the noise coming from his brother's room and had struck him with a rounders bat.
Following the verdict, Edward Jenkins, defending, said the case was "a tragedy" not just for Corin but for the rest of his family.