Who was Jack the Ripper? Various theories about his -- or her -- identity have circulated for decades.

There's more than meets the eye to Al Capone, the Prohibition-era leader of organized crime in Chicago.

Al Capone survived assassination attempts, brutal gang wars and an attack by a fellow inmate at Alcatraz. How did unprotected sex finally take down one of history's most notorious gangsters?

Uncover the true and horrific stories of 11 of the deadliest serial killers of all time, in this episode of History Countdown.