We're learning more about what's being called a pure "act of evil."
A house outside Seattle was deliberately blown up by Josh Powell. He and his two young sons in the house all lost their lives in the inferno.
Powell has been a suspect in the disappearance of his wife, Susan for more than two years—a mystery that has gripped the nation.
Moments before he deliberately blew up the house, Josh Powell emailed his lawyer this message: "I'm sorry, goodbye."
Nothing is left but the charred embers of Josh Powell's house. Fire officials told INSIDE EDITION's Jim Moret he used some kind of accelerant that literally blew up the house after he locked himself and his two boys inside.
The boys had just been dropped off for a supervised visit by a social worker who pounded on the door after smelling gasoline.
Just last week, Powell appeared at a court hearing trying to get custody of seven-year-old Charlie and five-year-old Braden.
Powell claims their mom went missing in December, 2009, after he took the boys on a midnight camping trip in the middle of a blizzard. He stuck to his story in court.
"I love my wife. I know my wife loves my children," he said in court.
Today, Susan's greiving father Chuck Cox, gave INSIDE EDITION a tour of the bedroom where the two boys slept when they stayed at his house.
Cox was fighting his son-in-law for custody. He also says the boys were beginning to articulate what happened the night their mother vanished. Shockingly, he said the boys remembered their mom was "in the trunk" of the family vehicle.
"They had gone camping. Their mother had been in the trunk and later, their mom and dad walked out into the desert and mommy got lost," said Steve Downing, the Cox family attorney
INSIDE EDITION spoke to Kirk Graves, who is married to Josh Powell's sister, Jennifer.
"It wouldn't surprise me that he wanted to hide the truth. If he wanted to kill himself, great, and that would have solved his problem. But he didn't need to take his kids with him," said Graves.
He says Josh Powell was probably worried about the lie detector and psychological testing that a judge had ordered him to undergo before he could regain custody of his boys.
"To think that anybody could have predicted that he could kill his boys in this way especially, no, I'm still in shock over it," said Graves.
The boys were taken away from Josh Powell after his father Stephen was charged with possession of child pornography on a computer in his home where the boys were living. He's pled not guilty.
Stephen Powell, you may remember, was obsessed with his daughter-in-law Susan and even wrote a bizarre love song for her that had the lyric: "I could love you in a secret way."
Now, as this mystery takes another horrific turn, Susan Powell's devastated father can only recoil at the loss, first of his daughter, and now of his two grandsons.