The unsolved murders of women around Green River near Seattle haunt investigators for decades - until crime scene science finally catches up.

A serial killer’s deadly road trip through Florida in 1990 leaves several men dead and spurs investigators to go undercover for an unexpected suspect.

Odd suspects, questionable confessions and ever-shifting stories confuse detectives in the hunt for a young Oregon woman's killer in the early 1990s.

A consequential letter surfaces with stirring claims and upends the seemingly closed case, calling into question the guilt of the convicted criminals.