more importantly greg oakes said they got nothing for testifying.m credible? >> i did. >> reporter: why do you believe some people and not others? >> we have to look beyond just do we believe somebody or not. is there information that they can provide that can be backed up by other independent evidence? >> reporter: the d.a. didn't think he could believe anything jennifer wescott had to say, and he came to question tonya's credibility, too. >> i don't believe in tonya priest and her story. she said that had heard these admissions back in 2006. and i asked her, why didn't you immediately come forward to the police? and her response was, i simply didn't believe him. >> reporter: and after reviewing all the evidence, he decided there was no there there. >> i was convinced that they had had the right person. >> reporter: what would the motive be for these two thibodeau brothers? >> unfortunately, dennis, there has been no obvious motive for all these years. >> reporter: months had gone by since tonya first called the d.a.'s office. now she got a phone c