There was nothing on the surface that raised red flags about Robert Hansen. The unassuming Anchorage native was married with children and was the successful owner of a bakery. But Hansen eventually confessed to killing 17 women in the Alaskan wilderness in a most heinous way.

Ken Rex McElroy, a bully who menaced the farming community of Skidmore, Missouri for years, was shot and killed on July 10, 1981 outside a local bar. Witnessing the murder were McElroy's wife and dozens of local residents. Yet the gunman has never been identified.

It's been nearly a decade since four bodies were discovered spread over a quarter of a mile stretch of beach in Long Island, New York. Since then, other remains have been found, with 10 victims or more now likely tied to a single perpetrator.

Israel Keyes—a murderer who perplexed even the FBI's top minds in criminal profiling—traveled America leaving 'kill kits' with weapons and other items in secluded locations, picking them up before abducting and murdering a chosen victim.

In 1978, four young people disappeared during their shift at a burger restaurant in Speedway, Indiana and turned up dead two days later. What happened remains a mystery and the case has yet to be solved.

How did Charles Manson, an illiterate ex-con, become such an influential cult leader and turn a group of peaceful hippies into cold-blooded killers? Journalist Tom O'Neill set out to answer this and more in his book, 'Chaos.' Read about Manson's early years—starting with his neglectful mother, then moving on to his stints in institutions for 'delinquent' children and ultimately, in federal prison.

During the 1970s, David Berkowitz, also known as 'The Son of Sam,' prowled New York City, fatally shooting couples in cars. By the time he was arrested in August 1977, he had killed six people and wounded seven others. Although the murders stopped after his arrest, several people who worked on the Son of Sam case are convinced Berkowitz didn't act alone.

Forehead mutilation, an LSD hamburger and a missing lawyer all made the Tate-LaBianca murder trial highly unusual.

Aiyana Gauvin, Adrian Jones and Roman Barreras are some of the high-profile cases from the past few years of children who were abused and ultimately killed by their parents. We speak with experts about why some parents unleash such extreme violence on their children.

It's hard to imagine there was once a time when women trusted serial killer Ted Bundy to take care of their children—but that's exactly what happened in the summer of 1975. Bundy would sometimes take two young boys to a local pool or the drive-in. Years later, one of those boys reflects on incidents that may have hinted at Bundy's dark and secretive world.