. >> reporter: it was a withering interrogation and bill kyne cracked. he changed his story and said he did, in fact, go into his bedroom after the fight with kevin. >> why would you lie to us about certain statements? >> got no logical explanation. >> detectives don't like to be lied to and here he's told you a lie. first statement, i'm not in the room. now you're sweating him -- >> and -- >> -- and he is in the room. >> and now he's in the room. and it's like, you know, "bill, you said you weren't in the room. what's going on? >> does he backpedal again from that story, detective? >> he does. he just says he's -- "i thought it would be better if i said i was in the room. >> reporter: if bill thought changing his story about going into the bedroom to check on diane made him look better, he was probably the only one. >> i have told you what really happened. >> which version are we supposed to believe? >> you haven't been truthful to us at this point. >> you see how this is going? >> uh-huh. >> you fail a polygraph. your dna is on her neck. his isn't. >>