One of the most unusual murder trials in US legal history is coming to an end in a Californian courthouse.

It involves two young men who are being tried for a murder which even the prosecution agrees they did not commit.

If convicted both defendants face up to 25 years in jail.

The case has triggered a debate over a rarely-applied legal doctrine called the "provocative act rule" which allows a person to be tried for murder if their actions created the situation which led to the crime.

Only the states of California and Maryland have the controversial rule.

The Solano County district attorney's office used the doctrine to charge David Moreno and Justin Pacheco, now both 21, with the 1997 murder of 17-year-old Jerry English.

Murder charges were brought even though Chad O'Connell, then 16, confessed that he had carried out the killing with an 11in knife during a fight.

Mr O'Connell eventually pleaded guilty to possession of a deadly weapon and was put on probation.

"It is a bizarre law being applied in a bizarre fashion with bizarre results in that the killer was set free," Barry Newman, the attorney for Justin Pacheco, said.

"That and the fact that the killer was set free was not the fault of the law but the fault of the district attorney seeking to apply this law."

Victim's friends accused of murder

This case began in November 1997 when Jerry English was killed after a brawl between two groups of teenagers in Vacaville, a town 50 miles (80km) northeast of San Francisco.

Mr O'Connell told police he stabbed the youth to protect a friend being beaten with a pipe.

Authorities decided Mr O'Connell had acted with justifiable force.

But prosecutors then decided to charge Mr Pacheco and Mr Moreno with the murder - even though the pair had driven their bleeding, dying friend to the hospital - because they charged that their actions led to the fight which resulted in the death.

Initially, a judge dismissed the charges, saying they had no merit.

A second judge overruled that decision and a jury convicted the pair in 1998 of second-degree murder and assault.

But last June the trial judge threw out the conviction on grounds of jury misconduct, after some jurors said they had been browbeaten into voting guilty.

The latest trial began at the beginning of January. Through it all, Mr Moreno and Mr Pacheco have been sitting in a county jail, unable to afford bail, according to their attorneys.

Race factor

Solano County prosecutors insist that the two were responsible for the crime because the pair started the fight that led to the death.

But defence lawyers also say race could be a factor. Both Mr Moreno and Mr Pacheco are Hispanic. Mr O'Connell is white.

"In California, unfortunately, if you are Hispanic you are just about automatically considered a member of some gang or another," said Leonard Oldwin Jr, a partner in the law firm representing Pacheco.

"You have to remember they let go a white, blond, blue-eyed kid."