Police Close Susan Powell Case, Offer New Details Josh Powell reportedly had an affair just months before his wife disappeared and his brother may have been "heavily involved" in getting rid of her body, Utah police revealed as they announced they couldn't solve the sensational case. The West Valley City Police Department on Monday opened its books on the investigation of Susan Powell's 2009 disappearance, after several years of second-guessing about why they never arrested her husband. Josh Powell killed himself and the couple's two young sons in an explosive house fire in Washington state last year. The tens of thousands of pages of documents, photographs and video, and interview notes and voice mail messages the department released depict an investigation that focused from its earliest days on Josh Powell. Detectives doubted his bizarre story that he left his sleeping wife at home in the middle of the night to take the boys camping in the Utah desert during a snowstorm, and they questioned his odd behavior in the days after the disappearance. The files discussed how detectives painstakingly followed up on tips they received from campers, hunters, prisoners and other law enforcement agencies and even psychics. Following Josh Powell's death last year - and his decision to make his brother, Michael C. Powell, the main beneficiary of his life insurance policy - police focused more closely on Michael Powell. He was interviewed numerous times last year after investigators determined he left his car at an Oregon junk yard weeks after Susan's disappearance - a fact police didn't learn until nearly two years later. While authorities believe the brothers were responsible for Susan Powell's disappearance, they said repeatedly Monday that they never had enough evidence to bring charges - an assertion that has been questioned in the past by legal experts as well as law enforcement in Washington state. "This is a circumstantial case, yes," said West Valley City Deputy Chief Phil Quinlan. The case file shows that in August 2010, police contacted a West Valley City woman, whose full name is redacted, after her phone number was discovered in Josh Powell's phone records. She told police she had a sexual relationship with Powell after meeting him through a dating service about six or seven months before Susan Powell disappeared. It wasn't until after she saw news coverage of the case that she discerned his true identity. The woman "advised she and Josh had sex five to six times in various areas of the Salt Lake Valley," and "stated Josh Powell paid a total of approximately $800 during this time frame," Detective Ellis Maxwell wrote in one report. She also gave detectives a tour of areas where she said they conducted their encounters - always during daytime, Maxwell wrote.