At a hearing the week before the fatal fire, Josh Powell was ordered to undergo a psychosexual evaluation and polygraph test in order to get his children back, after it was revealed police had found realistic computer-generated depictions of parent-child sex on his computer, Detective Ed Troyer of the Pierce County Sheriff's Department told The Associated Press.
The family of Susan Cox has said in the wake of Powell's death that West Valley City, Utah, police had been closing in on arresting Powell for the murder of Cox.
They said the children had begun to describe their mother being in the trunk of the car when the father took them on a late night camping trip in freezing rain the night their mother disappeared.
Charlie and Braden Powell were to remain with their maternal grandparents, Chuck and Judy Cox, until their father's next hearing, which was scheduled for July.
ABC News' Colleen Curry contributed to this report