Thanks to a "lurker" to this video of a talk in Las Vegas by Mark Galeotti, on his special subject. Intrigued that the city has the 'Mob Museum', formerly the National Museum of Organized Crime and Law Enforcement. See:

Mark's blogsite has his slim bio:

Link to the video (50 mins):

Curiously he relies on a conversation with a Chechen "hitman" who was in the USA for several years plus a jail term, before his extradition to Russia, where the case "fell apart" so he was back home in the post-Gorbachev Russia.