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.

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.

In three decades as an undercover operative for the Bureau of Alcohol, Tobacco, Firearms and Explosives, Vincent A. Cefalu risked his life investigating groups from outlaw motorcycle gangs to the Ku Klux Klan. Cefalu spoke with us about the undercover moments that frightened him most.

On February 1, 1890, Helen Potts, a young woman of wealth and privilege overdosed on morphine and died while attending a prestigious New York City finishing school. Her husband, a handsome med student named Carlyle Harris whom she had married in secret, had prescribed her some pills containing the drug after she complained to him about chronic headaches. But the pills contained enough morphine to kill a person—and Harris knew it. It was his plan all along.

Former FBI special agent John Douglas spent his 25-year career with the Bureau interviewing hundreds of America's most infamous killers, from Charles Manson and Ted Bundy to the 'BTK Killer,' Dennis Rader and more. The 'Mindhunter' author talks to us about his new book, 'The Killer Across the Table,' and his tried-and-true interview techniques.

The actor talks about his late wife Michelle McNamara's role in helping identify the Golden State Killer suspect.

In the fall of 2013, Americans were shocked to hear about the arrest of an elderly couple in their seventies, Gerald and Alice Uden, each charged with separate murders from decades prior. Ron Franscell's new book tells of the dark secrets this killer couple was able keep buried for more than 30 years.

Mafia 'freelance contractor' and actor Gianni Russo spoke to A&E Real Crime as he releases 'Hollywood Godfather,' a memoir that moves from his polio-afflicted childhood in the Little Italy section of New York City to friendships and feuds with legendary mob figures like Frank Costello and John Gotti.

What is evil—and how do we measure it? Is it more evil to abduct and torture a stranger for days before ultimately letting them go, or to fatally shoot a spouse in a fit of jealous rage? We speak to clinical psychologist Dr. Gary Bucato, co-author of the new book, 'The New Evil,' about how he determined what acts are more evil than others and why serial killers aren't all categorized the same way.

True-crime author Michael Arntfield talks about homicide detective Pat Postiglione, who headed up Nashville's cold-case Murder Squad and solved dozens of unsolved murders, and how the country-music mecca became a murder hub.