on, they could not find the evidence to arrest him. dave remains a free man. something that makes his own son, conrad very nervous. >> my suspicion was growing stronger and stronger. conrad toll police the night he discovered his mom were missing. he saw the night with his father and his girlfriend. >> at the time i thought my father and his girlfriend had poor taste. >> reporter: conrad spent that summer out. in august of 2006, two months after his mother's disappearance, child protective disappearance took 16 years old conrad to a foster home. there were just a few altercations kind of what my mom had gone to. investigators talked many times to dave's girlfriend, mary and eventually this exchange