Jana Monroe, one of the FBI's first female agents with the Behavioral Science Unit, on what it was like interviewing serial killers.

Jillian Lauren, author of 'Behold the Monster: Confronting America's Most Prolific Serial Killer,' speaks with A&E True Crime about her relationship with Samuel Little, the most prolific serial killer in U.S. history.

Was bullying during his early years to blame for Joel Rifkin becoming one of the most prolific serial killers in New York history?

Barbara Butcher, a former New York City death investigator, on what the work entails and which cases have stuck with her decades later.

Five of the Chicago serial killer's 33 victims from the 1970s remain unidentified, but the Cook County Sheriff's office is continuing the work to ID them.

In 2003, Steven Mack, a homicide detective with the Huntington Beach Police Department, took a leading role in retrying a twice-overturned murder case against Rodney Alcala. His efforts led to the uncovering of a prolific serial killer.

Susan Jonusas talks to us about her book 'Hell's Half-Acre' about a 'family' of four known as the 'Benders,' who were accused of murdering 11 people in Kansas but fled before they were prosecuted.

Read about the life and death of Tim McCoy, serial killer John Wayne Gacy's first known victim. Gacy murdered at least 33 boys and men between 1972 and 1978

During the 1990s and early 2000s, more than 30 women were targeted by serial killers, including Derrick Todd Lee, in the Baton Rouge area.

Dr. Marissa Harrison, an evolutionary psychologist and author, speaks to us about her research on female serial killers and how she was impacted by victims' stories.