A grand jury is hearing evidence from prosecutors to determine if oustedInterior Secretary Ryan Zinke lied to federal investigators about a Native American casino proposed for Connecticut, The Washington Post reported Friday.

Zinke’s decision to block the tribes’ operation and what he told federal investigators about the situation is now the focus of the grand jury proceeding, two sources told the Post.

Zinke in 2017 refused to grant a request from the Mashantucket Pequot and Mohegan tribes to run a commercial casino off reservation land in Connecticut in exchange for giving the state 25 percent of slot revenue. The operation required the approval of the Interior Department’s Bureau of Indian Affairs. The planned venture was strongly opposed by MGM Resorts International, which had a competing casino nearby in Massachusetts.

Interior staffers had recommended the tribes’ request to jointly operate their casino be granted, but Zinke refused. The tribes claimed Zinke’s decision was due to “improper” political influence. MGM was the second-biggest campaign contributor to Republican Dean Heller, who was a Nevada senator at the time and who reached out to Zinke before his decision, according to a lawsuit filed by the tribes.

Deputy Secretary of the Interior David Bernhardt also met in 2017 with a lobbyist for MGM Resorts, which was also a client of the lobbying firm that employed Bernhardt before he switched to government service, HuffPost reported at the time. Berhhardt, now the acting secretary, had agreed in writing not to participate in matters involving a former employer. Bernhardt and the lobbyist — who was hired by MGM specifically to battle the tribal casino — insisted that the meeting was a “social visit.”

The Office of the Inspector General of the Interior Department opened an investigation last year after the tribes’ complaint. OIG investigators believe Zinke lied to them during the inquiry, and the matter was referred to the Justice Department, the Post reported.

Zinke last month told the Post that he did nothing wrong concerning his rejection of the casino request. “I sided with a principle that I didn’t want to take a position on something that was off the reservation,” he said.

Grand jury witnesses have been asked if anyone influenced Zinke’s decision, according to the Post’s sources.