In his signature book, The Art of the Deal, Donald Trump boasted that when he wanted to build a casino in Atlantic City, he persuaded the state attorney general to limit the investigation of his background to six months. Most potential owners were scrutinized for more than a year. Trump argued that he was “clean as a whistle”—young enough that he hadn’t had time to get into any sort of trouble. He got the sped-up background check, and eventually got the casino license.

But Trump was not clean as a whistle. Beginning three years earlier, he’d hired mobbed-up firms to erect Trump Tower and his Trump Plaza apartment building in Manhattan, including buying ostensibly overpriced concrete from a company controlled by mafia chieftains Anthony “Fat Tony” Salerno and Paul Castellano. That story eventually came out in a federal investigation, which also concluded that in a construction industry saturated with mob influence, the Trump Plaza apartment building most likely benefited from connections to racketeering. Trump also failed to disclose that he was under investigation by a grand jury directed by the U.S. attorney in Brooklyn, who wanted to learn how Trump obtained an option to buy the Penn Central railroad yards on the West Side of Manhattan.

Why did Trump get his casino license anyway? Why didn’t investigators look any harder? And how deep did his connections to criminals really go?