AP

A file photo of missing Utah woman Susan Powell, whose family died in the explosion. Picture: AP Photo/Hardman Photography

Graham (Washington)- The long, bizarre case of a Utah woman missing for two years took a horrific turn on Sunday when a house explosion killed the woman’s husband and his two young sons, moments after the boys arrived for a visit that was supposed to be supervised by a social worker.

Authorities say it appears the husband, Josh Powell, blew the house up on purpose.

The Child Protective Services worker brought the two boys to Powell’s home, and Powell let his sons inside – but then blocked the social worker from entering, Graham Fire and Rescue Chief Gary Franz said.

The social worker called her supervisors to report that she could smell petrol, and moments later the home exploded. What’s left of the house was still smoking on Sunday afternoon, and fire crews were mopping up the scene.

Sergeant Ed Troyer, Pierce County sheriff’s spokesman, said e-mails Powell sent to authorities seemed to confirm that Powell planned the deadly blast. Troyer didn’t elaborate on the contents of the e-mails.

Jeffrey Bassett, who represented Powell in the custody case, said he received a three-word e-mail from his client just minutes before Powell and the two boys died. It said: “I’m sorry, goodbye.”

The remains of a house where an explosion killed Josh Powell and his two sons on Sunday, is shown from the air in Graham, Washington state. Picture: AP Photo/Ted S. Warren

AP

The e-mail arrived at 12.05pm on Sunday, about 10 minutes before the explosion, but he didn’t see it until two hours later, when others told him Josh and the boys had been killed. He said he knew Josh was upset after being ordered to undergo a psycho-sexual evaluation recently, but he didn’t see this coming.

Powell was under investigation in the disappearance of his 28-year-old wife, Susan, from their West Valley City, Utah, home in December 2009. He claimed he had taken the boys on a midnight excursion in freezing temperatures when she vanished.

The children, 5 and 7, had been living with Susan Powell’s parents since Josh’s father, Steven, was arrested on child porn and voyeurism charges last year.

On Wednesday, a judge had denied an attempt by Josh to regain custody, saying she wouldn’t consider returning the two boys to their father until he underwent a psycho-sexual evaluation.

“It’s the most horrifying thing you can imagine happening,” said lawyer Steve Downing, who represented Susan Powell’s parents, Chuck and Judy Cox, in the custody fight.

“The Coxes are absolutely devastated. They were always very fearful of him doing something like this, and he did it.”

Sergeant Mike Powell of the West Valley City Police Department in Utah, which is handling the investigation into Susan’s disappearance, said it was too soon to say how Josh’s death may affect their probe.

“Quite frankly, this has quickly unfolded up in Washington and we’re working through the details ourselves here,” Powell said. – Sapa-AP