Jack "Legs" Diamond was born Jack Moran in Philadelphia, Pennsylvania on July 10, 1897 to Irish immigrants, John and Sara Diamond. Jack was also known as Gentleman Jack or Gentleman Jim.
After his mother's death in 1913, he moved to Brooklyn, New York, with his father and brother. As a teenager, Diamond turned to street gangs and became involved in theft and violent crime. He was first arrested at the age of 17 for the burglary of a jewelry store.
No one knows how he received the nickname "Legs". Some speculate that it was his ability to outrun the law, while others believe it was his talent on the dance floor of the nightclubs he loved to frequent.
During the course of his mob career, Diamond was shot four times, recovering each time. As a result, he became known as the "clay pigeon of the underworld".
He was a popular figure to the public because of his flashy style and charismatic manner. He was also very popular with the press. In 1931 alone, Jack appeared in The New York Times on 103 occasions. Nineteen of those appearances were on the front page.
In the early morning of December 18, 1931, Diamond was shot and killed. The mystery remains as to who was behind the killing.
An article appearing in the Albany Times Union newspaper stated:
"Jack 'Legs' Diamond, survivor of a dozen skirmishes with the law and the lawless alike, today went from a clandestine tryst with Marion 'Kiki' Roberts, his showgirl sweetheart, to a tryst with death in an Albany rooming house.
"Unknown assassins, stalking down their prey with cool deliberation, pumped a stream of leaden pellets into the racketeer's head as he lay asleep in a small room at 67 Dove St.
"Death was instantaneous as the bullets furrowed the brain that had been set at rest a few hours earlier when a Rensselaer county Supreme court jury acquitted Diamond of a charge of kidnapping James Duncan, a Cairo youth."