Christopher Monfort, who is charged with killing Seattle Police Officer Timothy Brenton nearly three years ago, will plead not guilty based on reason of insanity, according to court documents filed in King County Superior Court February 1.
King County prosecutors say Monfort ambushed officer Brenton as he sat in his patrol car on Halloween night in 2009.
Law enforcement sources tell KING 5 they are not surprised and will now hire their own experts to evaluate Monfort.
Brenton was parked in Seattle's Leschi neighborhood after a traffic stop when Monfort drove alongside and opened fire, killing Brenton and grazing the neck of his partner, Officer Brit Sweeney, investigators said.
King County prosecutors are seeking the death penalty against him.
They said he was engaged in a "one-man war" against Seattle police. He is also accused of attempted murder in the firebombing of several police vehicles in a maintenance yard.
Police also said he had been preparing to make a last stand at his Tukwila apartment complex when detectives shot, paralyzed and arrested him.