It's worth mentioning that the skim was caused by Nevada's own form of 1920's Prohibition in America:
When gambling was legalized in Nevada in 1931, control was put into the state's Tax Commission. Control was lax: all they wanted was to tax casinos' profits. They welcomed the gangsters because they were bringing money into a state that was the most underdeveloped and underpopulated in America. The gangsters operated pretty much out in the open. This helped keep violence to a minimum, in part because the openness and legality of what they were doing cut down on the suspicion and jealousy that always cause violence in Mob circles.
But, the televised Kefauver hearings (1950-51) and McClellan hearings (1957) informed millions of Americans that organized crime was behind gaming in Nevada. So, in 1958,the State Legislture took control out of the Tax Commission and put it into a brand new Gaming Commission, which had the power to license key employees of hotels and casinos, and to exclude people with criminal records and/or reputations from even entering a casino--much less owning and operating one (the "Black Book").
The new Gaming Commission and its rules drove the mobsters underground--just as America's Volstead Act drove booze merchants underground. Now, instead of making their money legitimately (and paying taxes on the profits), the gangsters hired "legitimate" businessmen (like Glick) to front for them. They took their profits by skimming the casinos--simply filling suitcases and bags with money from the counting rooms before it was recorded and reported to hotel shareholders and the government. And when the gangsters were prohited from investing openly in hotel/casinos, they used "fronts" like the Teamsters Central States Pension Fund to invest for them. Of course, union treasuries and pension funds have always been tools of organized crime. But they often have "legitimate" people fronting them, so the Gaming Commission let them invest.