charles sebesta had argued graves' identical knife had inflicted 66 stab wounds the night of the murder. >> there's no doubt that that knife could have survived that. we had texas ranger testimony that it could have done it. >> reporter: but hanak, who is a former texas ranger himself, believes the knife would have left its mark on the killer. >> when you get down to the 10th, 11th, 12th stab wound, the knife becomes very slippery, becomes very bloody. the person that inflicted those wounds is also going to have an injury themselves. >> reporter: and did anthony graves have any injuries on his hands? >> none at all. >> reporter: did robert carter have any injuries on his hands? >> no. >> reporter: what does that tell you? >> that tells me that this is not the knife that caused those injuries. >> reporter: siegler thought any new case against graves would have to be built almost solely on robert carter's testimony, but that was before she found out how charles sebesta got that testimony from his star witness. he made a deal with mr. carter. >> and what a deal he made. >> reporter: sebest

charles sebesta had argued graves' identical knife had inflicted 66 stab wounds the night of the murder. >> there's no doubt that that knife could have survived that. we had texas ranger testimony that it could have done it. >> reporter: but hanak, who is a former texas ranger himself, believes the knife would have left its mark on the killer. >> when you get down to the 10th, 11th, 12th stab wound, the knife becomes very slippery, becomes very bloody. the person that inflicted those wounds is also going to have an injury themselves. >> reporter: and did anthony graves have any injuries on his hands? >> none at all. >> reporter: did robert carter have any injuries on his hands? >> no. >> reporter: what does that tell you? >> that tells me that this is not the knife that caused those injuries. >> reporter: siegler thought any new case against graves would have to be built almost solely on robert carter's testimony, but that was before she found out how charles sebesta got that testimony from his star witness. he made a deal with mr. carter. >> and what a deal he made. >> reporter: sebest

charles sebesta had argued graves' identical knife had inflicted 66 stab wounds the night of the murder. >> there's no doubt that that knife could have survived that. we had texas ranger testimony that it could have done it. >> reporter: but hanak, who is a