his name was ynobe matthews. >> he mentioned that he did attend this party. people who had attended, ynobe agreed to an interview, his down at the police department. he was friendly and cooperative. said carolyn had left the party before he had. >> he later left the party. went with another female that was at the party over to a convenience store that was close by and bought some cigarettes. >> ynobe gave the detective a dna sample and supplied the clothes he had been wearing. to verify his alibi, the detective pulled surveillance video from the convenience store, and noticed something. >> the clothing that he was actually wearing was different than what he had just told us. why is he not telling us the truth? >> ynobe claimed he had simply forgotten, and then handed the detective the proper clothing. no forensic evidence found on the clothes connected him to the crime scene. so this wasn't your big moment. >> no, it wasn't. >> the big moment did come, though. just a few nights later when the pieces of this puzzle finally came together. >>> coming up, an arre

and kristen should have no guilt over that. >> with the casey family as witnesses, ynobe matthews wascuted three years later. if there is a lesson to take from this story, it is one that comes directly from a survivor herself. someone who has learned the hard way to cherish life's moments, each and every one. >> it makes you realize how fragile your life is, and that anybody can take it in a moment's notice. the story for them, that's it. that's their life's story. the final chapter has been written. but for me, i get to keep going on. >> what would you call yourself? >> i mean, people have called me a survivor. i would call myself lucky. >> that's all for this edition of "dateline extra." i'm tamron hall. thank you for watching. >>> somebody like me with my mentality does not belong in society. >> after a horrifying act of violence, the kokomo slayer displays his brutality for all to see. >> most murderers get 60 years. i got sentenced to 72 years. >> two brothers pay a harsh penalty for their dealings in