SAN FRANCISCO -- Prosecutors have dismissed murder charges against four alleged ex-members of the Black Liberation Army accused of killing a San Francisco police officer in 1971.

The charges were dismissed Monday against Henry Jones, Ray Boudreaux, Richard Brown and Harold Taylor in the killing of Sgt. John V. Young during an attack on a police station.

Another defendant, Anthony Bottom, pleaded no contest Monday to conspiracy to commit voluntary manslaughter in Young's death as part of a deal with prosecutors.

Bottom and Herman Bell were convicted of murdering two New York City police officers and are currently serving prison sentences.

Bottom had been serving 25 years to life at Auburn Correctional Facility since Nov. 16, 1977, but in 2007, Cayuga County Judge Thomas Leone executed a California warrant to extradite him to San Francisco.

At the time of the extradition hearing, Bottom argued that he was serving time at a California jail when the murder occurred and therefore could not conspire in the murder.

"I couldn't possibly have been engaged in conspiracy with these men," he said in Cayuga County Court in March 2007.

But Leone said his role was not to determine the validity of the charges, as that was outside the scope of his authority.

"Quite honestly, I agree with you," Leone said, "You weren't there, but that's for Californian courts to decide."

In addition to Bottom, Francisco Torres, of New York, is the other defendant charged in the San Francisco murder.