and so i just kept, no, it can't be it can't be. i just kept hoping i did everything i could >> reporter: but even as she ran down leads herself, it seemed to tara that lisa, her sister in law, gavin's wife, wasn't searching. >> so he disappeared and you couldn't give up on the possibility he was out there somewhere and lisa could and i wondered whether there were ever sort of dark nights to your soul where you thought i wondered if she had something to do with this >> it crossed our minds all the time it just did. i mean, did i think that she could ever be the one responsible, the physical? no but somehow, it kept playing back why won't you search. why? the only way somebody doesn't look for you is if you already know definitively -- >> yeah.