DAVIS, Calif. (AP) -- Among the evidence recovered from the home of a man who shot and killed a rookie California police officer were two unregistered guns and a letter claiming police had been bombarding him with ultrasonic waves.
Police in the city of Davis on Saturday released the letter they say was written by Kevin Limbaugh.
The 48-year-old killed himself Thursday after fatally shooting Officer Natalie Corona.
Limbaugh wrote police targeted him with ultrasonic waves for years, saying "I can't live this way anymore."
Investigators have not identified a motive for the ambush shooting of the 22-year-old officer as she investigated a car accident.
Detectives also found two semiautomatic handguns not registered to Limbaugh.
Limbaugh was ordered last fall to surrender a semiautomatic rifle after he was convicted in a battery case.