A retired police investigator thinks the same person who killed JonBenét in 1996 could have killed two other girls in 1984 and 1993.

Historian Hallie Rubenhold, author of the book, 'The Five: The Untold Lives of the Women Killed by Jack the Ripper,' believes the victims of Jack the Ripper weren't all sex workers—they were just women who were asleep.

Ever since 'Golden State Killer' suspect Joseph DeAngelo was arrested in April 2018 after being tracked down with the help of an online DNA database typically used for tracking genealogy, crime-solving via genetic genealogy has increased. Last year, investigators made more than 20 arrests in cold cases. But given that there are thousands of murders in America every year, of which 40 percent go unsolved, why aren't DNA databases being used to solve even more crimes?

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.

Samuel Little murdered as many as 93 women, some almost a half century ago. But all these years later, he still remembers their faces. A&E True Crime spoke with sociology and criminology professor Jack Levin, who explained how serial killers remember their victims and why these details are so important to them.

Serial killer Ted Bundy had a chameleon-like ability to deftly change appearances—whether physically or with the help of costumes and props—which helps explain why the vicious killer was able to evade police for so long.

Kerri Rawson, daughter of Dennis Rader, otherwise known as serial killer BTK, talks to A&E True Crime about her struggle to reconcile the man who raised her with the one who, for years, terrorized her hometown of Wichita, Kansas.

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.

A&E True Crime takes a look back at the horrific crimes of Canadian serial killer and 'Cold Case Files' subject Ronald Glenn West and investigates where is he now.