>> these people might literally get away with murder. >> hello and welcome to "dateline extra." i'm craig melvin. jack jessee was a doting grandfather jack jessee at the helm his big and blended california family seemed like one happy bunch. then jack was found stabbed to death in his living room and police wondered if the jessees weren't as close as they seemed. the case went unsolved for years, until a determined detective hatched an unconventional plan to catch jack's killers. here's keith morrison. "deadly conspiracy." >> reporter: the game is called