One of the most important figures in 1940s Las Vegas gambling got his start on the right side of the law, crossed over to the wrong side, and then came back. Guy McAfee was a vice squad commander in the Los Angeles Police Department, who, it was discovered, had ownership interests in several illegal casinos. Resigning rather than facing corruption charges, he moved to Las Vegas, where he was involved with several legal casinos. He’s best known as the founder of the Golden Nugget.
There’s lots more about the early figures of Las Vegas gambling in Roll the Bones: The History of Gambling.