GRAHAM, Wash. Feb. 9, 2012 -- Josh Powell's sister had once suspected him of murdering his missing wife, but now – despite killing his two sons in a fiery explosion – she believes he had nothing to do with Susan Cox's disappearance.
Alina Powell conceded to ABC News that she was suspicious of her brother when his wife vanished in 2009.
"I was. I had my doubts," she said.
But in the following two years, those doubts had been erased.
"I scrutinized him pretty deeply. I watched him when he would talk, when he would interact with anyone else. I had my doubts," Alina Powell said. But, she said, "I never, ever heard anything that was remotely suspicious in I don't know how many months."
Josh Powell was the sole person of interest in the disappearance of Susan, a label that Alina Powell said tore him apart, leading him to kill himself and his two sons, Charles, 7, and Braden, 5, this past weekend.
She depicted her brother as a victim.
"I think this was the act of somebody who had been so damaged by the lack of due process, so harassed and abused and lied about that he just reached a point of feeling like there was no... I don't know," she said.
The family of Susan Cox have 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. That was the night that their mother disappeared.
But Alina Powell, and other members of Powell's family, say the police tormented Powell. They accused the West Valley City police of interfering with the custody battle between Josh and Susan's parents over the couple's two sons. The police department sent a letter to the Washington family court where custody hearings were held, claiming that images found on Josh's computer in 2009 signified danger to the boys if they were left in Josh's care.
"I think he must have just felt that there was only one way left for him to protect his sons, from the pain, from all the emotional and physical pain they've been experiencing," Alina Powell said.
Alina Powell was one of several people to receive a voicemail from her brother just minutes before he blew up his home Sunday with his sons inside. In the voicemail, Josh Powell said good-bye. His alarmed sister called 911, but responders arrived on the scene after the explosion had occurred.
"When I got there I just stopped in the middle of the road. I said it looks like his home exploded and it's just practically gone," she said. "I wake up and I feel like it didn't really happen. It just takes a few minutes for it to sink in."
While some have characterized the murder-suicide as an admission of guilt by Powell, Alina said she still believes her brother was innocent.
"I just miss them all so much. They were my boys. All three of them, they were my boys," she said.