. >> reporter: eventually watts asked to speak with his father, ronnie watts, who has just flown in from carolina. >> choked both of them to death? >> i freaked out and did the same thing. >> oh my god. if she killed bella and cece, choked them to death, you lost it and choked her? that's rage. oh, son. >> reporter: it's a stunning statement. chris watts claims shannan had attacked the kids and he killed her in a fit of rage. agents re-enter the room. they aren't buying chris' story. >> i think we're very, very close to the truth but we're not there yet. >> i'm not a monster. i didn't kill my babies. >> reporter: honing in on where the bodies are. >> whereabouts is shannan and the girls? can you mark it for me? "s" for shannan, okay. where are the girls at? >> reporter: watts marks the spots with their officials. the two girls in separate oilre shnanhaow missing the scene. >> where he pointed to where he put your daughter and your granddaughters -- >> sickening, isn't it? >> how do you react to that? >> devastated. you know? >> he is a monster. how do you -- put someone you love -- into

. >> reporter: eventually, watts asks to speak with his father ronnie watts, who has just flown in fromunusal move, allowing a third party into the interrogation room. >> both of them? >> yeah. >> she choked both of them to death? >> i freaked out and did the same thing to her. >> oh, my god. so, if she killed bella and cece, choked them to death, you lost it and choked her, or what? >> mm-hmm. that's rage. >> oh, son. >> reporter: it's a stunning statement. chris watts claims shanann had attacked the kids. and he killed her in a fit of rage. cbi agents re-enter the room. >> i saw the monitor. bella's covers were pulled off. and she was laying there. so i went over to cece's. and she was in there with her on top of her, choking her. i freaked out. i ran in there and got on top of her. >> what did you do? >> i did the same thing to her. >> who, shannan? >> yes. i'm not that person. >> he speaks quietly. he's not very animated. he's just kind of laying it out, matter of factly. >> was it a choke like this? or, like, a headlock. >> a choke. >> you killed her with one hand or two hands? >>