A grand jury has been hearing evidence about whether former Interior Secretary Ryan Zinke lied to federal investigators about a casino petition he denied, the Washington Post reported on Friday, citing two individuals briefed on the matter

The Interior Department’s inspector general believed Zinke may have lied to its investigators about the petition and referred the matter to the Justice Department, as the Washington Post previously reported.

At issue is a petition from two Native American tribes, the Mashantucket Pequot and Mohegan, to build a casino 12 miles away from an existing MGM casino in Connecticut.

Zinke denied the request after meeting with lobbyists representing MGM, prompting the Native American tribes to file a lawsuit.