(Rick Egan | The Salt Lake Tribune) Chuck and Judy Cox, parents of Susan Cox Powell, talk about the disappearance of their daughter last December during an interview in their home in Puyallup, Wash., on Thursday. (Rick Egan | The Salt Lake Tribune) Josh Powell, looking at a family photo from his 2002 college graduation, said his wife, Susan, is “extremely unstable,” and that he believes mental illness drove her to leave her family behind. Josh Powell is living in Puyallup, Wash., with his father and children. (Rick Egan | The Salt Lake Tribune) Josh Powell looks at photos of him and Susan from his college graduation in 2002 at his home in Puyallup, Wash., Nov. 4. (Rick Egan | Tribune file photo) Steve Powell, father of Josh Powell, talks in 2010 about the disappearance of Susan Powell. Powell, 61, was convicted of voyeurism and is due out of prison in May 2013. (Rick Egan | The Salt Lake Tribune) A sign on the window of Chuck Cox's family van, parked in the driveway of their home in Puyallup, Wash. (Rick Egan | The Salt Lake Tribune) Judy and Chuck Cox, the parents of Susan Cox Powell, hold a photo of their daughter during an interview in their home in Puyallup, Wash. A flier for Susan Powell is posted on a light post in the Washington state neighborhood of the missing woman's husband, Joshua. (Rick Egan | The Salt Lake Tribune) Chuck and Judy Cox, parents of Susan Powell, talk about the disappearance of their daughter last December, during an interview in their home in Puyallup, Washington, Thursday, November 4, 2010. Al Hartmann | Salt Lake Tribune Chuck and Judy Cox, the father and mother of missing Susan Powell, speak of the ongoing investigation into her disappeance at a friends home in West Valley City on Friday September 10th. They live in Puyallup, Washington. The sign on their Jeep is a reminder to keep the investigation alive and not to forget about Susan's disappearence. Chuck Cox, right, the father of Susan Powell, who was reported missing Dec. 7, 2009, in Utah, is helped by family friend Michael Gifford, left, as he talks to reporters about a photo of his family, with Susan Cox shown at upper right, Thursday, Dec. 17, 2009, in Puyallup, Wash. Powell's family said Thursday they are saddened but not surprised that her husband Josh Powell has been named a person of interest in the investigation. (AP Photo/Ted S. Warren) (Djamila Grossman | The Salt Lake Tribune) Nia Hellewell, 7, daughter of one of the best friends of Susan Cox Powell, releases balloons with others to mark Powell's birthday at West View Park, in West Valley City, Saturday, Oct., 16, 2010. A crowd of about twenty attended a vigil for Susan Cox Powell at an LDS chapel in Puyallup, Wash., on Saturday to remember her three months after her disappearance. Stephen Brashear Scott Sommerdorf | Salt Lake Tribune SUSAN POWELL SEARCH Searcher Dan Despain (cq) of Fountian Green pilots his flying parachute above others as they scour the areas in and around Simpson Springs Saturday, 4/10/10 for any signs of Susan Powell. (Tribune file photo) Jennifer Graves talks about her brother Josh Powell and dad Steve Powell at her home in West Jordan in 2010. (Djamila Grossman | The Salt Lake Tribune) file A photo of Susan Cox Powell is set up during a ceremony to mark her birthday with a balloon release at West View Park, in West Valley City on Oct. 16. This undated picture made available by Hardman Photography shows Susan Powell. The 28-year-old mother from the Salt Lake City area was reported missing on Monday, Dec. 7, 2009. (AP Photo/Hardman Photography, Amber Hardman)