The trial has begun in the case of an American teenager accused of shooting dead a gay classmate.

Lawrence King, 15, who self-identified as gay and wore feminine clothing, was shot twice in the head on February 12th 2008 during a lesson at E.O. Green Junior High School in Oxnard, California.

His classmate Brandon McInerney, who was 14 at the time, was charged with first-degree murder and hate crime.

It is alleged that King made sexual advances to McInerney and the younger boy believed King had a crush on him.

The trial, in Chatsworth, California, was due to begin today.

Witnesses to the killing said McInerney had sat down at a desk behind King at a morning computer class before pulling out a handgun and shooting him twice in the back of the head.

He then dropped the gun and walked out of the room, his classmates and teacher said.

Despite his age at the time, McInerney is being prosecuted as an adult and could be sentenced to 50 years in jail.

He does not deny the shooting but his lawyers argue he is guilty of voluntary manslaughter because he was humiliated by King’s sexual advances.