GRAHAM, Wash. – Days after a judge ruled against him in a child custody hearing, a father and his two young sons were killed Sunday when police said he appeared to intentionally blow up a house with all three inside — a tragic ending to a bizarre case that began more than two years ago when the man’s wife went mysteriously missing in Utah.

A social worker brought the two boys to Josh Powell’s home for what was to be a supervised visit, and Powell let his sons inside — but then blocked the social worker from entering, Graham Fire and Rescue Chief Gary Franz told The Associated Press.

The social worker called her supervisors to report that she could smell gas, and moments later the home exploded.

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

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

The email arrived at 12:05 p.m. Sunday, about 10 minutes before the explosion, but he didn’t see it until two hours later, when others told him Powell and the boys had been killed.

Bassett said he knew Powell 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-year-old Braden and 7-year-old Charles, had been living with Susan Powell’s parents since Josh Powell’s father, Steven, was arrested on child porn and voyeurism charges last fall.

On Wednesday, a judge had denied an attempt by Josh Powell 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.”

Bassett said he represented Powell free of charge because “every parent deserves the right to an attorney.” Powell called or emailed him at least once a day, and often more than that, and in their conversations “he never once admitted doing anything regarding Susan. In fact, he denied it.”

Kirk Graves, 39, of West Jordan, Utah, the husband of Josh Powell’s sister, Jennifer, said he and his wife were stunned by the news.

“We never contemplated the idea he would do something like this. You just don’t expect it from a father,” he said.

“His world was falling apart around him and he was going to lose his boys and get arrested for Susan’s disappearance,” Graves said. “He’s a narcissist and he has no love for anyone but himself.”