But that last conclusion drew a strong response from Chuck Cox, the missing woman's father.
"We told them Josh was capable of killing the children," Cox said. "We had warned them of that very possibility. We told them of our concern that if Josh Powell was cornered and was going to lose the children or be arrested, he would be capable of killing the children and himself. And that is exactly what happened."
Cox said he and his wife, Judy, shared that concern with caseworkers, psychologists, police and attorneys involved in the case after receiving temporary custody of their grandsons in September 2011.
"They heard us, they knew about it and they chose to dismiss it," he said. "And, as a result, our grandchildren are dead."
Powell killed his children and himself on Feb. 5 in a fire set at his rented home in Graham, Wash. The children had just arrived for what was to be a three-hour supervised visit. Powell let the boys, who had run ahead of the visitation supervisor, into the home and then shut out the worker. The fire exploded moments later.
The murder-suicide occurred four days after a Pierce County Superior Court judge declined to return the children to Josh Powell's care and ordered that he undergo further evaluation based on newly disclosed pornographic images found on a computer seized from his Utah home.
The review committee recommended that the state's child welfare agency provide ongoing training on domestic violence to caseworkers and increase communication between child welfare workers and law enforcement when parents are targets of active criminal investigations.
While West Valley City police spoke regularly to Washington social workers and told them they believed Josh Powell killed his wife, "the communication generally consisted of law enforcement expressing an opinion as to Mr. Powell's involvement in Susan Powell's disappearance," the committee said.
The committee said hard evidence gathered by police in the case "would have raised specific safety concerns for the children, but that information was not made available to [the] Children's Administration prior to the children's death."
That included information contained in warrants used in an August 2011 search of the Puyallup, Wash., home Josh Powell and his sons shared with Steve Powell, Josh's father. A Pierce County Superior Court judge issued the warrants and sealed them at the request of West Valley City police because of the ongoing investigation. The information might have shaped safety assessments for the children, what kind of services to provide Josh Powell and how to structure visits, the report said.
The committee, however, acknowledged that presented a potential problem since any disclosures from police would have been shared with all parties, including Josh Powell, as part of the child welfare dependency hearings.
The West Valley City police department responded to the report Thursday night, stating it had provided information to Washington state authorities regarding the welfare of the two boys.
"Although the dependency proceedings were primarily a matter for the State of Washington ... Information determined to be pertinent to the boys' health, safety and welfare was released by this department when it was appropriate," wrote Sgt. Mike Powell, spokesman for the West Valley City police in a news release. He is not related to the Powell family.
The West Valley City police statement says the children's welfare was paramount throughout the investigation into the disappearance of their mother and puts the blame for their deaths squarely on Josh Powell.
"At no time did the West Valley City Police Department receive any indication that Josh Powell would murder his two sons. Josh is solely responsible for his horrific actions back in February of this year and individually responsible for the murders of Charlie and Braden," the statement reads.
Cox disagreed that caseworkers didn't have enough information about law enforcement's investigation.
"They had enough knowledge [that] they should have seen this as a possible outcome and made sure visitation was correctly supervised or limited," he said.
The committee also said that intake workers handling the Powell case checked "no" on universal domestic violence screening questions used to gauge safety threats to children, including one that asks, "Has anyone used or threatened to use physical force against an adult in the home?"
But given the widespread knowledge of Susan Cox Powell's disappearance, that question could easily have been answered "yes," the committee said, which would have prompted further investigation into domestic violence, if any, in the family.
Josh Powell and his sons moved to Washington in January 2010, weeks after Susan Cox Powell disappeared. According to the report, Child Protective Services received four referrals about disconcerting comments Charlie made at school between March 2010 and June 2011. But the boy's remarks did not meet neglect or abuse standards and, while the reports were forwarded to law enforcement, no further action was taken.
That changed in September 2011 when the Pierce County Sheriff's Office placed the boys in protective custody after arresting Steve Powell on voyeurism and child pornography charges. Officers told caseworkers it did not appear the boys had been exposed to any child pornography but said law enforcement was still reviewing computers seized from the home earlier. At the request of West Valley City police, no further information was shared with caseworkers, the report said.
After six days in foster care, Charlie and Braden were placed temporarily with the Coxes. Superior Court Judge Kathryn Nelson initially allowed Josh Powell to have a weekly supervised visit with his sons, which took place at a Children's Administration office and then at a Foster Care Resource Network office.
Child Protective Services made an "unfounded" finding as far as child neglect in October, but Josh Powell agreed to an order continuing the dependency case while he worked to have the boys returned to him. Josh Powell moved into the rented home and asked that the supervised visits be held there.
Child welfare officials agreed to the request after speaking to the boys' guardian ad litem, a psychologist who evaluated Josh Powell, the visitation supervisor and others. It also considered the impact notoriety surrounding the Powells was having on other families who were visiting their children at the Foster Care Resource Network's office. In December, Josh Powell received court approval for an additional weekly visit with his sons, which were held at the home of a local pastor who had befriended the family.
Although not required, the administration did not consult with law enforcement about those decisions, the report noted.
Law enforcement officers told the committee they were unaware the supervised visits had been moved to Josh Powell's home and would have expressed concern had they known.
Recommendations of Washington state panel
In cases with related, active criminal investigations, the child welfare administration should consult with law enforcement before changing visitation between a parent and a child.
Due to the "intrusive" nature of psycho-sexual evaluations, visitation should be re-evaluated after such exams and before the next visit.
Ongoing training and consultation about domestic violence should be provided to child welfare workers.
Judges should articulate reasons for a child placement in the court record when a parent objects to that placement.