bum-pa-dum, bum-bum-bum-bum ♪ >>> jacksonville beach had been home to tiffany zienta.ad turned on her. did you think there's a chance i could get arrested? >> yes. for something i didn't do. >> reporter: but she wast arrested and neither was anyone else in the months following corey parker's murder. a year went by. state attorney angela corey. so this wasn't solved after the commercial break? >> oh, no. no, no. we went into this knowing we were in for the long haul. with that phrase we knew it was going to be a marathon, not a sprint. >> reporter: they had their list of possible suspects, but they didn't have the evidence or the science yet to definitively link anyone to the crime. >> dna testing was actually in the middle of evolving at that time. >> reporter: eventually the science and the evidence came together. investigators recovered a strand of foreign hair from corey's underwear. they believed that single strand was rich in dna. >> it had been clearly ripped out of a head. >> reporter: likely, they believed, the killer's head. now they had to test it against the