detective bernie nelson had investigated hundreds of murders.o keep the recurring images of death at arms length. but this case was different. he was the father to a teenager around karissa lofton age. >> ma'am i've been shot. me and my mother have been shot. i'm bleeding to death. >> that poor little girl in her bedroom. she has the gumption to get on the phone and call you. >> it hurts to listen to the 9-1-1 call because you can feel and hear the fear the fear in her voice. >> even though nothing was taken it seemed clear the killer broke into the house. in fact the burglar alarm had gone off, but it was disabled in under one minute. and that put karen's thing kion loft and at the top of police is persons of interest. list he lived in the house. he knew the code. police brought him in for questioning. >> does your mom set the alarm for the? house all the time? >> one of the detectives plainly said, everybody in that room things it's you, you're the only one that had access to the code. >> would you have hurt your mom and sister? >> you would'v