How It Really Happened - Season 4

During a terrifying three-day period in late August 1990, five college students were found brutally murdered in Gainesville, Fla.; panic filled the usually sunny city as investigators searched to find the serial killer before he struck again.

During a terrifying three-day period in late August 1990, five college students were found brutally murdered in Gainesville, Fla.; panic filled the usually sunny city as investigators searched to find the serial killer before he struck again.

Elizabeth Smart was kidnapped from her Salt Lake city home in 2002 and snatched from her bed at knifepoint by a mysterious man in the middle of the night; to the public it seemed as if she had vanished into thin air.

For nine months in 2002, 14-year-old Elizabeth Smart was the most famous missing child in America; kidnapped by Brian David Mitchell, she was forced up into a hiding spot in the mountains behind her home, assaulted and forced to be his second wife.

On Oct. 25, 1994, Susan Smith reports that a carjacker has abducted her two young sons, Michael and Alexander; this report sets off a nationwide search for the boys; while the world waits for news about the boys, investigators deliver shocking news.

For nine days, the nation waits for news as to the whereabouts of missing 3-year-Michael and 14-month-old Alex Smith; then, there's a shocking break in the case; the boys' father, David, shares his heartbreaking story; a look at the investigation.

On Oct. 28, 2007, 23-year-old Stacy Peterson, the wife of veteran police sergeant Drew Peterson, goes missing. as police launch an intensive search to find Stacy, the case raises shocking new questions about her husband.

Actor-musician David Cassidy ("The Partridge Family") experiences the pressures of fame as a teen idol in the 1970s; in the end, his death is surrounded by mystery, leaving his family, friends and fans with more questions than answers.

On April 19, 1995, Timothy McVeigh, a 26-year-old U.S. army veteran, detonated a 7,000 pound truck bomb outside the Alfred Murrah Federal Building in downtown Oklahoma City, claiming the lives of 168 innocent people. We take a look back at the events that led up to the largest domestic terrorist attack in the history of the United States.

In an exclusive prison interview, Timothy McVeigh himself describes how events in his personal life - and in the ever-changing world around him - inspired him to take action against his fellow Americans. We also hear from survivors of the bombing, as well as family members of victims, who describe the full impact of that fateful day.