Former Interior Secretary and current GOP congressional candidate Ryan Zinke and his then-chief of staff lied repeatedly to investigators about their attempt to quash a tribal casino in Connecticut, the Interior Departments internal watchdog concluded in a report released Wednesday.

The report from the Office of Inspector General offers the most damning evidence in long-running allegations that Zinke personally blocked the casino project, a partnership between the Mashantucket Pequot and the Mohegan tribes, at the urging of lobbyists from competing casino giant MGM Resorts International, then misled federal investigators about his actions.