dr. skaggs stamp. and dr. skaggs, if you look at that, was not a doctor as of that date. he was still a teenager. he didn't become a licensed doctor until years later. >> reporter: so your theory is >> absolutely. even deeper. starting with that so-called teen doctor's signature. this old news article in the archives led us to a major discovery. the real dr. skaggs -- now living in florida. and guess what? he was a full-fledged doctor when diane was born. >> that's a false comment. at the time of that delivery i was 27 years old. >> reporter: he agreed to look over diane's birth certificate for us. >> yes, this is my signature on the birth certificate. and it's similar to my signature right now. >> reporter: as for watkins' other claim, that zella's signature on the birth certificate was forged since she insists she never signed it, we asked her to give us extensive handwriting samples. then had an independent handwriting expert take a look. and his conclusion? zella's handwriting is definitely consistent with that signature on the birth certificate. dr. skaggs confirms h