The man who shot and killed rookie officer Natalie Becky Corona of the Davis (CA) Police Department reportedly left a strange one-paragraph letter face up on his bed before killing himself.

The department released the note on Monday, according to CBS News.

"The Davis Police department has been hitting me with ultra sonic (sic) waves meant to keep dogs from barking," Kevin Douglas Limbaugh said in the letter. "I notified the press, internal affairs, and even the FBI about it. I am highly sensitive to its affect (sic) on my inner ear. I did my best to appease them, but they have continued for years and I can't live this way anymore."

Davis police say that Limbaugh approached Officer Corona on a bicycle as she was investigating a three-car traffic collision, opening fire in an unprovoked ambush attack.

The subject fled into a nearby home, where he remained barricaded for a period of time. Police sent in a robot, which found him dead from a self-inflicted gunshot wound.