Josh Powell painted himself as a tortured man, ridiculed without reason in the disappearance of his wife, steadfastly insisting he was innocent until the end.

Yet the investigation and autopsy reports released late Monday show the acts of a violent man who meticulously planned the double murder-suicide of himself and his two young sons, culminating Sunday in Powell setting his house ablaze and taking a hatchet to his children's necks.

Ultimately, Powell and both boys died of smoke inhalation, Pierce County Medical Examiner's Office investigator Melissa Baker said Monday evening.

But they also suffered "chop injuries" that contributed to their deaths, 7-year-old Charles was struck on his neck and 5-year-old Braden had injuries to both his head and neck, Baker said.

Pierce County Sheriff's Detective Ed Troyer said investigators found a hatchet that they believe was used on the boys.

"We recovered a hatchet, a small ax," he said. "It was right there with" the bodies.

Fire crews recovered two five gallon gas cans used to ignite a fire that killed Josh Powell and his two sons.

Troyer said it appears one of the cans was ignited in the center of the house near where the bodies of Powell and his sons were discovered.

Listen to Sgt. Ed Troyer with latest details of Powell case

Troyer added that there was no gun found in the house and the victims did not have gunshot wounds. The medical examiner determined Josh Powell's cause of death was suicide by carbon monoxide poisoning, from the fire he had set inside the home.

Powell's lawyer said he did receive an email moments before the home exploded "I'm sorry, goodbye," it read. And Troyer said they're starting to learn more about other emails sent just minutes before the gas cans were ignited.

"They dictate what to do with the utilities, what do to with his money, what to do with certain aspects of his life. None of these emails arrived anywhere where anyone could do anything about it, but they do show that he was intending on doing this before it occurred."

In at least one email, he wrote that he couldn't live without his boys, Troyer said.

But, he added, "There's no indication about Susan in anything that we've found so far."

ABC News obtained what it said Tuesday was a voicemail Josh Powell sent to family members. In it Powell said he couldn't live without the boys and didn't want to go on anymore.

"I'm sorry to everyone I've hurt," he is heard saying. "Goodbye."

Troyer said they also have evidence Powell donated some of the boys' toys and games to Goodwill in the days before their deaths.

So far, investigators have not found anything in the house that will lead them closer to Powell's missing wife, Susan Cox Powell. While we may never get those answers, a Pierce County Prosecutor Mike Lindquist says Josh Powell's confession was the murder of the couple's two children.

"I don't know what goes on in the mind of somebody as sick and evil as Josh Powell, but I do think it's fair to call that a confession to the murder of Susan Powell," said Pierce County Prosecutor Mark Lindquist. "I think it's pretty safe to infer from this suicide-homicide that Mr. Powell had something he was trying to hide and something he wasn't wanting to face."

Listen to Prosecutor Mark Lindquist

Chuck Cox said that the summer after his daughter disappeared, Braden drew a picture at day care of a van with three people in it, and told caregivers who asked him about it that it was a picture of his family going camping: "Mommy's in the trunk," the boy reportedly said.

But the boys had not recently made more comments to that effect, Charles Cox said, contradicting earlier remarks by his lawyer, Steve Downing, who told The Associated Press that the older child had recently mentioned their mother being in the trunk.

West Valley City, Utah Police Chief Buzz Nielsen said Utah authorities would continue with their investigation, and hoped to make an arrest in the Susan Powell case this year.

"On a criminal case of this nature, you've got one shot. You've got to make sure everything is done right," Nielsen said. "Our case is not closed."

Steven Powell, Josh's father, may be the only one with any answers as to why Josh made the decision to kill his boys on Sunday.

Detectives reportedly want to question Powell's father, Steve Powell, about Susan's disappearance. He described Steve Powell as another "person of interest" but noted the elder Powell is "not in our sights" in terms of any potentially imminent arrest.

Steven Powell is now jailed and facing child porn and voyeurism charges. He once claimed that he and Susan Powell were falling in love and even implied a sexual relationship had occurred.

Troyer said Steven Powell was put on suicide watch in custody after he was told of the deadly blast.

"Steve Powell didn't seem very upset by the news, but was angry towards authorities who notified him," Troyer said.

"Rarely do we see crime as extreme as the murder of two children, fortunately," said Lindquist. "I would hope that if Steven Powell has any information that might help shed some light on this or bring some closure on this, he would share that information, but I just don't know what he's got at this point."

Sunday's tragedy has left the Coxes devastated. They spoke to reporters Monday to give a glimpse of the lives the boys led.

They said the boys played happily and didn't want to visit their father when the time came for their weekly Sunday visit. But Judy Cox said she talked them into going, and she now regrets it.

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The Associated Press contributed to this report.

MyNorthwest.com, Staff report

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