The FBI is investigating a deadly fight at one of California’s most violent prisons, along with allegations that guards at another of the state’s high-security lock-ups set up brawls between prisoners. The fights at the High Desert and Pelican Bay penitentiaries were the latest to come under investigation by the FBI, which announced yesterday that it’s widening its probe into the California prison system. A day earlier, eight guards from Corcoran State Prison pleaded innocent in federal court to staging gladiator-type fights between inmates of rival gangs. In a February 4 clash at High Desert in the northeast corner of California, 10 Asian prisoners attacked eight Latino prisoners in an exercise yard. Guards trying to end the fight shot and killed David Torres, a 29-year-old Latino, and wounded two other prisoners. The FBI is investigating whether the guards were justified in shooting Torres, and may expand its probe to other disturbances at the prison.