Susan Powell Mystery: Police Search the Home of Missing Utah Mom's Husband and Father-in-Law

While Josh Powell denies involvement, investigators are combing the home.

Aug. 25, 2011— -- Dozens of investigators and members of the Pierce County Sheriff's Department are searching the Washington state home of the husband and father-in-law of missing Utah mom Susan Powell, ABC News affiliate KOMO in Seattle reported today.

Investigators and forensic specialists were combing the Puyallup, Wash., home, which Powell's 35-year-old husband, Josh Powell, shares with his father, Steven Powell, and has been living with the couple's two young sons, Charlie and Braden.

Josh Powell and his father were being detained while investigators executed a search warrant, the Associated Press reported.

Susan Powell was last seen in her home in 2009, but hasn't been seen or heard from since. While her husband has not been arrested or charged in her disappearance, police said he continues to be considered a person of interest.

Josh Powell maintains that he had nothing to do with the 2009 disappearance of his "unstable" and "very sexual" wife.

"Everyone who knows me knows that I would never hurt her and I would never hurt my boys," Powell said in said in an interview with ABC News. "I would never hurt anyone."

Steven Powell, Susan Powell's father-in-law, told ABC News that he and his son's wife had a highly flirtatious relationship that Josh didn't know about. He alleged that his missing daughter-in-law would frequently make passes at him and that he had a relationship with her that was "a little beyond the pale."

"There was really a disconnect between the Susan who was a faithful, loving wife, and the Susan who was a very flirtatious, sexual being," Steven Powell told ABC News' "Good Morning America." "Father-in-law - daughter-in-law flirting with each other, maybe some sexual touching or whatever. And-- I enjoyed it, frankly. Susan was a joy to be around in so many ways, not just those ways."

Susan Powell, then 28, was last seen on Dec. 6, 2009, at the West Valley City, Utah, home she shared with her husband and their two young sons, Charlie, then 4, and Braden, then 2.

Josh Powell told authorities that he had been camping with the boys -- in the midst of a blizzard -- the night his wife vanished.

Powell described his missing wife as an erratic and depressive person who contemplated suicide at several points in her life and would leave the house barely dressed.

"She has walked out the front door in her underwear, starting walking down the street," Powell said. "And at the time when all this stuff was happening, it was mortifying to me. And I was trying to stop it. ... I've tried to protect her from doing things that I thought might embarrass her or our family, in that respect."

Powell told ABC News that he felt his wife might still be alive. Though he said that he was unaware of any time that his wife was unfaithful to him, he wondered if she left him and their two young children for another man.

"She's a very sexual person," he said.

Josh Powell's characterization of his wife was supported by his father, Steven Powell, who spoke with ABC News about his relationship with his daughter-in-law – one that he claims was very flirtatious. He also says that the two were in love.

He told ABC News that his son was unaware of the relationship he says he had with his daughter-in-law.

"Josh wasn't aware of a lot of these things at first because the first two or three years of his marriage -- it was really pretty much not something that really came to light," Steven Powell told ABC News. "We interacted in a lot of sexual ways because Susan enjoys doing that."

Steven Powell plans to post his daughter-in-law's teenage journals on the website; according to the Salt Lake Tribune, he says that the journals show that his daughter-in-law is capable of walking out on her husband and their two sons.

He has publicly theorized that she disappeared with a man from St. George, Utah, who disappeared from a Christmas party abruptly the same night she vanished.

Susan Powell's parents, Chuck and Judy Cox, maintain their daughter was a stable person -- and feel Josh Powell should be doing more to help police solve this mystery.

"I see Josh as a desperate person," Chuck Cox told ABC News. "He needs to find some way to excuse his behavior or deflect attention, and he is unwilling to cooperate with the police department.

"I do not believe that he went camping in the middle of the night with two young boys. I know Susan wouldn't let him do it," he said.

ABC News' Lauren Effron contributed to this report.