The state Supreme Court ruled Thursday that King County prosecutors can seek the death penalty against a man accused of killing a Seattle police officer.

In a unanimous decision, the high court overturned a February King County Superior Court ruling that had found that Prosecutor Dan Satterberg's decision to seek the death penalty against Christopher Monfort was invalid because he relied on a mitigation investigation by his office, rather than waiting for evidence from the defense. The Supreme Court reinstated the death penalty notice, and sent the case back to the trial court to proceed.

Monfort is accused of killing Officer Tim Brenton and wounding another officer as they sat in a patrol car Oct. 31, 2009, as well as setting fires to police cars earlier that month. Monfort was wounded by police during his arrest about a week later in Tukwila. He is paralyzed from the waist down and confined to a wheelchair.

Nearly 10 months after Monfort was arraigned, Satterberg announced he would seek the death penalty. At the time, his office had conducted interviews with more than two dozen of Monfort's friends, acquaintances and family members to see if there was mitigating evidence. Satterberg had not considered any mitigating evidence presented by defense attorneys, because they hadn't given him any.

Under state law, mitigating circumstances that could merit leniency include mental disturbance or disease.