Signs of a Psychopath

An 18-year-old man is reported missing in North Dakota. Witnesses lead police to a young man with a history of violence, who didn't work alone.(S04,E13)

When a 19-year-old Colorado woman vanishes, the suspect is her troubled former classmate who has a past filled with homicidal urges toward women.(S04,E09)

A man finds his family slaughtered in their home. Police discover the oldest son, 16-year-old Gavin Smith, killed them so he could see his girlfriend.(S04,E10)

A mother vanishes after meeting with her divorce attorney and estranged husband. A psychopathic game of cat and mouse with investigators ensues.(S04,E15)

Hikers in Portland discover the decomposed body of a strangled young girl. A month later, another woman turns up brutally murdered in same fashion.(S04,E16)

A 33-year-old calls 911 to report his girlfriend missing. A failed polygraph test leads detectives to suspect that he might be hiding something.(S04,E17)

Martine Bernard's family reports her missing while she is six months pregnant. Days later, her father also vanishes. Is her husband responsible?(S04,E18)

When a grandmother doesn't return home from her morning walk, police uncover that the man responsible for her disappearance is a pathological liar.(S04,E19)

Experts examine the early warning signs in psychopathic killers apprehended as teens and young adults, a parent's worst nightmare.(S04,E12)