gina watson. >> it became, i would say almost an obsession of looking for information. >> they quickly became seasoned investigators, scouring the internet, tracking down leads. evidence that gina believed poked holes in the theory that the family voluntarily went to mexico. and there was more. >> like all of their craig's list purchases, if a family was planning to disappear, why were they buying so much on craig's list? countertops, microwaves, things for the new house, going on all the way up to the disappearance. >> and then there's this. >> hey, don't go anywhere without the double stroller. >> what would be the need to walk across the border, why not just bring your car, what would be the need to go at that time of night? >> did you ever believe they disappeared intentionally on their own. >> no immediately i felt like something terrible happened to them. >> but what and by whom? >> what's up, dudes? >> early on, friend and business associate chase merritt was top of the list. >> detectives looking at joseph mcstay's business relationships. >> he spoke to us in his only televisio