>> his name was dirty john. >> this woman knew him all too well. >> i started snooping and i found everything. >> this reporter made some unnerving discoverses, too. the story of his dirty deeds riveted the nation in a hit podcast. >> this is dirty john. >> but dirty was about about to turn dark. >> he's got duct tape. he's got all the tools ready to kidnap her. >> would this mom and her daughters learn the truth in time? >> she was in a panic. she said i saw john outside in a car. >> a story ending in savagery that would stun even police. >> there's no way he gets away with this unless he kills her. woke to "dateline." after a string of failed relationships, deborah finally thought she found her mr. right.