>> reporter: debra was dumbstruck. tony? melissa? >> he would have no reason to do this to melissa. she's never done anything to him. >> reporter: so you're telling the detectives, "you're looking at the wrong guy." >> yeah. >> reporter: did tony know melissa? >> he had met her a few times, you know, over the years, but we weren't social. >> reporter: debra told police she and tony had been married for 17 years and had four children. they had separated more than a year earlier. tony had then moved into a house in miami gardens with a friend. for twenty years, he'd worked for florida east coast railways hauling freight. >> you know, he basically drove a train for a living. >> reporter: police checked him out on their computer. has he any priors? >> none. no priors. >> reporter: detectives went to talk to tony and recorded the conversation. >> how well did you -- do you know this -- your -- debra's -- debra's friend? >> melissa. i know her from her. i've seen her a few times. >> you guys ever have any problems, maybe? something like that? >> never. never. i don't think i ever spoke to her more than two words.