that supposedly she had taken with her. >> when "dateline" continues. >>> the year was 2004 and aaron candelario was 11 years old. his parents had recently separated. one day after a weekend at his dad's house, aaron went home to find -- >> there was just a note on the coffee table that was in kind of sketchy handwriting. nevertheless said, i love you, my boys, i'm taking off. >> his mother dena was simply gone. aaron was devastated. >> what did your father suggest may have happened to her? >> that she possibly had moved to missouri. a guy she had been talking to online for quite some time, maybe she ran away to be with him. >> a missing persons case was open but nothing came of him. >> aaron and his brother moved in with ralph. aaron couldn't move on. she had to have left some trail somewhere. barely a teenager, he taught himself every web search engine, looked for years. but found no sign of his mom online. and a terrible suspicion took hold of him, hardened into something like certainty. his mother must be dead. his father must have done it. >> and after that, it became more of, okay, where w