"The Davis Police department has been hitting me with ultra sonic (sic) waves meant to keep dogs from barking", the letter said. They say they believe the suspect left it on the bed face up for officers to find after he took his own life.
Investigators also found two semiautomatic handguns, a 9 mm and a.45 caliber, inside the home.
Corona started volunteering as a community service officer with the Davis Police Department after she graduated from high school and for a time work at the department even after funding for her position ran out.
On Thursday night Davis police officer Natalie Corona was processing the scene of a 3 vehicle accident, when witnesses say that Limbaugh was lurking in the shadows and then approached Corona, shooting her once in the neck and then several more times after she went to the ground.
The newspaper said authorities have not determined where Limbaugh obtained the weapons he used in the Thursday night attack that killed 22-year-old Officer Natalie Corona in the college town of Davis.
In the letter, Limbaugh said he notified internal affairs, the media and the Federal Bureau of Investigation.
"As far as the firearms that we found, he has no firearms registered to him at this time", Doroshov said. "I am highly sensitive to its affect [sic] on my inner ear", the letter reads.
Officers reported hearing a gunshot and later found Limbaugh dead inside, Pytel said.
In November, Limbaugh was ordered to turn in a black.223 Bushmaster AR-15 semiautomatic rifle.
They went on to issue sympathies for officer Coronas family saying her death was an "incredible, senseless tragedy". "I did my best to appease them but they have continued for years, and I can't live this way anymore", said the note, which was signed, "Citizen Kevin Limbaugh".
"She was a rising star in the department", Pytel said.
More than 1,000 mourners attended a Saturday evening vigil for Corona. Her father, Merced Corona, served 26 years as a Colusa County Sheriff's deputy, the Beereported. She had just completed six months of field training when she was ambushed while checking driver's licenses during a routine call.