The official announcement from Pierce County stated that Josh Powell committed suicide and his two children, Charlie, 7, and Braden, 5, were murdered.
While both boys has a cause of death listed as carbon monoxide poisoning, the medical examiner said there were "other significant factors" to their murder. From the medical reports, it appears Josh Powell tried to kill his sons with a hatchet before the flames engulfed them all.
According to the medical examiner, Josh failed by only wounding the boys horribly, but not killing them. Pierce County Sheriff Public Information Officer Sgt. Ed Troyer said there were wounds to the boys' neck and heads.
Police say they recovered a hatchet at the scene of the house fire and believe that was the cause of the injuries.
Sgt. Troyer said that investigators found evidence that Powell purchased and placed ten gallons of gasoline inside the home before his sons Charlie and Braden arrived for a supervised visit on Sunday.
A social worker had just arrived at the home Sunday afternoon when the boys ran inside and Josh locked himself and the boys inside. The social worker smelled gas just before an explosion and flames engulfed the home.
"This is definitely a planned event," said Sgt. Troyer. "It was going to happen no matter who was here."
Josh moved with the children to a home in Washington state but lost custody to the children's grandparents after police said they found child pornography in the house. Josh's father, Steven Powell, was charged with possession of child pornography.
Earlier this week Josh Powell was ordered to undergo a psycho-sexual evaluation by the judge handling his custody case.
Susan Powell has still not been located. Police have conducted a number of searches in remote areas outside of Salt Lake City but have not located any remains.
Stay with ABC 4 for more on this developing story. More detailed coverage on this case can be found at the Susan Powell section of ABC4.com.