A mistrial was declared yesterday in the case of a US teenager accused of murdering a gay classmate.

Jurors deliberating charges against 17-year-old Brandon McInerney could not decide whether he was guilty of first or second-degree murder or voluntary manslaughter.

McInerney was 14 when he shot 15-year-old classmate Larry King in the back of the head during a lesson at E.O. Green Junior High School in Oxnard, California, in February 2008.

He admitted manslaughter but denied murder.

The trial, which has been heard over the past month in Chatsworth, California, was told that the younger boy had snapped after King had teased and sexually harassed him.

Testimony focused on a motive for the killing, with a number of teachers testifying that more should have been done to prevent King from wearing make-up and women’s clothes.

King identified as gay but some teachers claimed his behaviour and demeanor was making him a target for bullying and was provoking angry reactions from other boys.

McInerney was tried as an adult for the killing. In defence, the court heard that he had suffered a violent and neglectful upbringing and had acted without thinking when he pulled the trigger.

The prosecution said that the killing had been pre-meditated, as McInerney had told a classmate the day before what he planned to do. The court also heard that white supremacist materials had been found in his bedroom.

Prosecutors must now decide whether to re-file murder and manslaughter charges against the teenager.

If convicted of first-degree murder, he faces 50 years in prison.