Chuck Cox will pass through Boise on a grim journey to try and find more clues to whether she's alive or dead.
"Right now it's a missing persons case," Cox told KBOI News on the phone as he was leaving Pendleton, Oregon. "We don't have a body and I'm going to hold out hope until we find a body."
Police in Utah recently closed the case on Susan Powell and released a video she made in 2008 in which she indicated a troubled relationship with her husband Josh Powell.
Josh Powell was the focus of the investigation until he killed himself and the couple's two children last year in an explosive house fire in Washington state.
Police believe Josh's brother Michael helped dispose of Susan Powell's body.
Cox says sniffer dogs recently found the scent of decomposing remains in Michael Powell's abandoned car in Pendleton.
Michael Powell committed suicide several months ago.
Along with his daughter Denise and two private investigators, Cox is going to travel a 500-mile stretch on the I-84 corridor, passing out flyers with photographs of the people involved, hoping to jar memories and uncover fresh leads,.
"I'm going to find my daughter," Cox said. "I am determined to find my daughter. If I end up being Don Quixote tilting at windmills, so be it."
Cox also hopes to meet with local law enforcement officers as he passes through Boise on his way to Tremonton, Utah. He's convinced Susan was transported against her will on I-84 between Tremonton and Pendleton.