SEATTLE — Convicted cop killer Christopher Monfort was found dead in his cell Wednesday morning at the Washington State Penitentiary in Walla Walla, according to a spokesman for the state Department of Corrections.

Monfort, who was convicted in 2015 of aggravated first-degree murder for the ambush killing of Seattle Police Officer Timothy Brenton on Halloween night 2009, was serving a life sentence. Paralyzed below the waist by a gunshot he suffered during his arrest in Tukwila, Monfort’s health had deteriorated by the time he stood trial in King County Superior Court.

Jeremy Barclay, communications director for the Department of Corrections, said Monfort was found dead in his single-person cell at 7:45 a.m. Wednesday. Prison staff began CPR but Monfort was pronounced dead by medics, he said.

There was nothing suspicious found in Monfort’s cell and there were no indications of self-harm, Barclay said.

Brenton’s brother, Matt Brenton, was in a meeting when he received a text message Wednesday notifying him that Monfort was dead.

“After the trial, we really didn’t think about him all that much,” said Brenton, referring to his mother, Penny Brenton, and sister, Betsy Porter. “While this is not closure at all, it closes a chapter. We will, just as we’ve always done, be celebrating Tim and honoring Tim.”

Brenton also offered condolences to Monfort’s family: “We know his family is hurting and mourning and our thoughts are with them,” he said.

In addition to aggravated murder, Monfort was also convicted of two counts of attempted first-degree murder for wounding Brenton’s partner, Britt Kelly, and, later, for pointing a handgun at a homicide sergeant investigating Brenton’s death. He was also convicted of first-degree arson for setting a fire and detonating pipe bombs that destroyed a handful of police vehicles at the city’s Charles Street maintenance yard nine days before Brenton was killed.

But the jury found him not guilty of attempted first-degree murder for what prosecutors argued was his intent to kill officers responding to the fire scene.

Monfort had pleaded not guilty by reason of insanity to all five felony charges. His attorneys claimed Monfort believed he could end police brutality if enough police officers were randomly killed.

After his conviction, jurors unanimously spared Monfort’s life and sentenced him to life in prison without the possibility of release.

Monfort was left a paraplegic after he was shot twice when he pulled a gun on Seattle Police Sgt. Gary Nelson, who was with two other homicide investigators following up on a tip about the car used in Brenton’s killing, when they encountered Monfort outside his apartment on Nov. 6, 2009. The shooting occurred just as a memorial service for Brenton was concluding at KeyArena.

In a 2010 Seattle Times profile, Monfort complained about police brutality, but declined to talk about the charges against him. “The things I’m accused of are selfless acts,” he said. “I didn’t get anything out of them. I’m not accused of robbing banks or stealing.”

During the penalty phase of Monfort’s trial, defense attorney Carl Luer said that in addition to his paralysis, Monfort suffered from chronic pain and a constant battle with skin and urinary-tract infections.

“Life behind bars is no picnic for anybody,” Luer told the jury. “It will be worse for Chris.”

On Wednesday, Luer — who has since moved to Colorado — said news of Monfort’s death “comes as kind of a gut punch.”

“We knew he wasn’t going to live to a ripe old age due to his various ailments,” Luer said, expressing condolences for Monfort’s family, especially his mother who regularly visited her son, first in the King County Jail and later, in prison.

Still, Luer said, “I’m stunned … I certainly didn’t expect to get this kind of news so soon after trial.”