Jerry Markling, head of the Nevada Control Board gaming unit that investigates criminal regulation violations in casinos throughout the US state of Nevada, is to retire, according to the Las Vegas Sun newspaper. Markling has headed up the enforcement division of the state’s Gaming Control Board for the past eight years and has been employed by the board for 20 years. The division gathers intelligence on organized criminal groups that are involved in gambling activities and picks potential candidates for its ‘Black Book’ – a list of individuals banned from casinos. It also settles disputes between players and casinos, conducts…