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Sheldon Adelson, chairman of US-based firm Sands Las Vegas.

Yesterday, the Newt Gingrich team bought millions of dollars of airtime in South Carolina, thanks to a last-minute donation of $5 million. It came from one of the world's richest men - a Las Vegas casino magnate named Sheldon Adelson. That money's been spent on ads attacking Mitt Romney. To learn more about Sheldon Adelson and his ties to Newt Gingrich, we check in with Jon Ralston. He's a columnist for the Las Vegas Sun.