History's Greatest Mysteries: Season 6, Episode 3

6 - 3: The Valentine's Day Massacre

On February 14th, 1929, one of the most shocking murders in mob history goes down in Chicago--and becomes known as the Valentine's Day Massacre. The 20s and 30s are full of gangland murders, but the Valentine's Day Massacre is considered the most brutal -- and the toughest to solve. So who carried out the Valentine's Day Massacre? And why?