'48 Hours' Richard Schlesinger investigates 'Knock Knock' Saturday Jan. 12, 2019

48 HOURS on CBS. The next episode is called, "Knock Knock" that will air this Saturday at 10/9 p.m. 

CBS says, "Can a podcaster and a driven detective using cutting-edge technology solve a stone cold double murder? 48 Hours - correspondent Richard Schlesinger investigates."