The murder of teacher's aide leaves a hole in the heart of her small community; as rumors spread about suspects, the actual perpetrator slips further away.

Father and teacher are found hanging naked from a tree with the letters F-E-D on his chest; with barely any evidence to work with, investigators turn to these letters for answers.

A single mom vanishes without a trace; foul play is confirmed when a truck toolbox opens with her body inside; homicide detectives investigate men she matched on dating sites, men from work, and a lover with a violent past.

A 20-year-old woman sets out on her bike and never returns; her body is found a few miles from the house while a gunshot wound to the head; years go by without any evidence or leads, until new investigators and technology break the case.

A navy lieutenant is murdered while deployed out to sea; arsenic poisoning is the cause of death; investigators discover he had more than his fair share of enemies, but it takes years before investigators discover what really happened to him.

A building manager finds the lifeless body of a young woman in the bathtub; when questioned, an ex-con living downstairs, lies to police; the lies do not prove murder and the case goes cold, then a new forensic tool examines the evidence.

A wounded woman crawls to call 911; her husband, who wants a divorce, gets a hard look from police, but he has an airtight alibi during the murder; forensic science of ballistics draws a direct connection.

A murder victim's final moments are caught on tape. The crime scene looks like a clear robbery-murder. Text evidence at first points to a jilted lover, but will his alibi check out?

A religious woman is shot execution style in the suburbs of Michigan; surveillance video reveals it was trio of killers; eventually, detectives get a break: a handwritten note.

Three sex workers are murdered and left along a river; a serial killer was on the loose; and, for years the perp was never identified.

He is a sex offender and a murderer who attacks in a terrifying rage. This predator manages to evade capture for years, but he leaves evidence behind - his palm print. Detectives are determined to put a face to the print.

A house fire kills the only doctor in a small town. An arson investigation leads to the son of the doctor's nurse. But when his alleged accomplice walks free, the prosecutor is worried this might have been a miscarriage of justice.

A young woman is found murdered on the side of a rural driveway. The victim had been out with friends. The investigation would remain unsolved. Until three decades later, when forensics from an unrelated crime helps breaks the case.

A hearing impaired 77-year-old on a road trip is shot to death. Why? Because the man cannot hear his assailant's demands. Random murders are among the hardest crimes to solve, but investigators are determined to bring this case to justice.