The Night Stalker, sentenced to death in 1989 for 13 murders, escaped execution when he died of natural causes in 2013.

Some of the most infamous criminals in history experienced murders first-hand before they starting doing the killing themselves.

Glynn Martin is a retired officer from the Los Angeles Police Department and the author of 'Satan's Summer in the City of Angels' about the local community's response to the 'Night Stalker' serial murders. Martin shares his experience as a young cop in the L.A. area during Richard Ramirez's reign of terror with A&E True Crime.

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.

Serial killer Richard Ramirez, otherwise known as 'The Night Stalker,' terrorized California in the mid-1980s with a series of rapes and murders. A number of women who survived his attacks mentioned his rotten teeth, among other details, helping police create a profile of the suspect.

Dr. Ashley Hampton, a licensed psychologist who works in the prison system with both victims and perpetrators of violent crime, tells us about how the traumatic childhoods of Charles Manson, Aileen Wuornos and Richard Ramirez may have shaped their adult behavior.

Ted Bundy received hundreds of love letters while behind bars. Richard Ramirez married one of his 'fans.' Criminologist Dr. Melissa Hamilton talks to A&E True Crime about the psychology behind why some women love serial killers.

A&E True Crime talks with Dr. Scott Bonn, criminologist and author of the book, 'Why We Love Serial Killers' about what he thinks were the powerful catalysts for the makings of a serial killer.