Jurors were deadlocked on a 12th charge - the attempted murder of a different detective.
Nicholas John Smit, 41, was found guilty Monday of several bizarre attacks that included improvised booby traps and the firing of a World War II-era bazooka at a police station.
Authorities said the attacks were focused on a detective in Hemet who had arrested Smit on a drug charge in 2009.
Over the next six months, members of that detective's anti-gang task force were targeted in several suspicious incidents, including arsons and attempted shootings.
In one instance, natural gas was rerouted into the office of a gang task force and rigged to explode. In the bazooka attack, a training rocket was fired from the roof of a nearby market and started a small fire.
Smit faces multiple life terms in prison at his sentencing, scheduled for Dec. 2.
Smit's alleged accomplice, Steven Hansen, is being tried separately.
The Associated Press contributed to this report.