Question: Who is Bugsy Siegel's friend and fellow gangster whose employee was murdered by Siegel in 1939?

Context paragraphs:
The Bugs and Meyer Mob: The Bugs (Bugsy) and Meyer Mob was a Jewish-American street gang in Manhattan, New York City's Lower East Side.  It was formed and headed by mobsters Bugsy Siegel and Meyer Lansky during their teenage years shortly after the start of Prohibition.  The Bugs and Meyer mob acted as a predecessor to Murder, Inc.

Cohen crime family: The Cohen crime family, or the Siegel crime syndicate, was an Italian-American Mafia / Jewish Mafia crime family created by New York Jewish American mobster Benjamin "Bugsy" Siegel in the early 1930s.  Siegel ran Los Angeles and later Las Vegas' illegal gambling and prostitution rings with his lieutenants Mickey Cohen, David Berman, Harold "Hooky" Rothman, Moe Sedway and boss of the L.A. family Jack Dragna.

Paul Kelly (criminal): Paul Kelly (born Paolo Antonio Vaccarelli; December 23, 1876 – April 3, 1936) was an Italian immigrant who founded the Five Points Gang in New York City after starting some brothels with prize money earned in boxing.  It was one of the last dominant street gangs in New York history; Kelly recruited young men who later became prominent criminals of the early 20th century, including Johnny Torrio, Al Capone, Lucky Luciano, Meyer Lansky, Bugsy Siegel and Frankie Yale.  Kelly was said to support election of Democratic Tammany Hall politicians with his gang's activities at elections.

Virginia Hill: Virginia Hill (August 26, 1916 – March 24, 1966) was an American organized crime figure.  A courier, she was famous for being the girlfriend of mobster Bugsy Siegel.

Lansky (film): Lansky is a 1999 American made-for-television crime drama film.  Directed by John McNaughton, it stars Richard Dreyfuss as the famous gangster Meyer Lansky, Eric Roberts as Bugsy Siegel, and Ryan Merriman as the young Lansky.

Bugsy Siegel: Benjamin "Bugsy" Siegel (February 28, 1906 – June 20, 1947) was a Jewish American mobster.  Siegel was known as one of the most "infamous and feared gangsters of his day".  Described as handsome and charismatic, he became one of the first front-page celebrity gangsters.  He was also a driving force behind the development of the Las Vegas Strip.  Siegel was not only influential within the Jewish mob but, like his friend and fellow gangster Meyer Lansky, he also held significant influence within the Italian-American Mafia and the largely Italian-Jewish National Crime Syndicate.

Harry Greenberg: Harry Schachter or Harry "Big Greenie" Greenberg was an associate and childhood friend of Bugsy Siegel, and an employee of both Charlie "Lucky" Luciano and Meyer Lansky.  On November 22, 1939, Greenberg was murdered by Bugsy Siegel and Whitey Krakow.  Siegel was eventually tried for the murders of Greenberg and Krakow, but was not convicted.

The American Gangster: The American Gangster is a 1992 American crime documentary film directed by Ben Burtt and written and produced by Ray Herbeck Jr.  The documentary is narrated by Dennis Farina and explores the lives of America's gangsters like Pretty Boy Floyd, John Dillinger, Al Capone, and Bugsy Siegel.  It was directly released on VHS in 1992 and later released as part of a DVD box set in 2006.

Bugsy (disambiguation): Bugsy is a 1991 film about the American gangster Bugsy Siegel.

Bugsy: Bugsy is a 1991 American crime-drama film directed by Barry Levinson which tells the story of mobster Bugsy Siegel and his relationship with Virginia Hill.  It stars Warren Beatty as Siegel and Annette Bening as Hill, as well as Harvey Keitel, Ben Kingsley, Elliott Gould, and Joe Mantegna.  The screenplay was written by James Toback from research material by Dean Jennings' 1967 book "We Only Kill Each Other".

Supporting paragraphs: Harry Greenberg Bugsy Siegel
Answer: Meyer Lansky