Each episode of “One Deadly Mistake” follows a homicide investigation where police work tirelessly against the clock to solve a complex case, until they discover a piece of evidence left behind that exposes the identity of the calculated killer.  In the premiere episode, Kathy Blair, a well-known and beloved member of the Austin, TX community, is found brutally murdered in her own home on a chilly afternoon in December 2014.  As investigators process the puzzling crime scene, the clues point in several different directions.  They are convinced they’re on the hunt for a meticulous killer who has gone to great lengths to cover his tracks.  But when an elderly couple in the same neighborhood is also found dead a week later, detectives work fast and furiously to track down the killer as the community awaits in fear for answers.  One by one, as suspects are interviewed and evidence is tested, detectives begin to hone in on their killer when a surprising piece of evidence is discovered exposing the killers careless One Deadly Mistake.