gina watson. >> it became, i would say almost an obsession of looking for information. >> they quicklyseasoned 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 are taking a close look at joseph mcstay's business relationships. >> he spoke to us in his only t