>> i believe that she had. >> so detective carter wondered if keith griffith had manipulated and liedan, had keith lied to him, too? maybe it was more about what keith hadn't said. rewind to that moment when the detective had dropped what should have been devastating news on keith. >> the investigation has shown that, that foul play is involved. >> okay. >> did he ask you the questions, what happened? what are you telling me here? she was killed? >> no. >> you'd expect that, right? julie was shot by an intruder? what's going on? >> right, there was no questions to that. >> but if keith griffith was somehow involved in his wife's murder, how on earth had he pulled it off? after all, he was hundreds of miles away at that hotel the night of the crime. unless, of course, he wasn't. >>> coming up, a security video surprise. >> scrolling through the tape. >> going through, going through. >> and then when did your bingo moment come up? >> and then a twist rocks the entire griffith family. >> we were all frantic. we had no idea how it could have happened. >> when "dateline" continues. got sim