and he looked at me and -- we don't know, keith, i can't tell you anything. >> keith bjerk last saw his son just the night before, june 10th, 2012. it was 11:00 at night. >> he was going to run out to a gas station. he said i'll be right back. i said okay, i'll see you in the morning, son. and i gave him a hug and kiss good night. and i was watching tv on the couch. he picked me up and shook me like that, said love you, dad, i'll be right back. >> his parents would later learn that at the gas station christian ran into a friend and ended up going to a house party. his body would be found a short distance away. what killed this healthy 18-year-old was a mystery that was about to strike this small midwest community again. >> we need an ambulance. we have a kid here who's not breathing. >> okay, where's the house? >> it's east grand forks. i don't think he's breathing at all. >> no, he's dead. we need somebody now. >> i know. >> can you guys start cpr with him? >> it was three days before eli's birthday. >> he would be 18? >> yeah. he wanted to go to grand forks to see his cousin and spend