but they didn't believe a word of his story or that his concern for heather was genuine. >> the reason you were freaking out is because she was dead. your actions after that make no sense. everything else after that was alibi. >> okay. so what did i do with her? >> that's what we're asking, chris. >> reporter: chris was sticking to his story, but the biggest break in the case was about to happen. what chris didn't know is that while detectives were turning up the heat inside the interrogation room, outside they sent some cadaver dogs over to the mall to sniff around his car. and now the team at the mall wanted to speak with detectives immediately. >> they said the dogs just hammered his car. they said they're all over it. >> reporter: they found the scent of human remains. >> i don't know why cadaver dogs hit on my car. >> i do. they don't just hit. they don't just pick cars out of the blue. >> what is it they're trained to detect? i mean --