Deputy Attorney General Jeffrey A. Rosen deferred a bid from line prosecutors to move forward with possible criminal charges against former interior secretary Ryan Zinke, saying they needed to gather more evidence and refine the case, according to three people familiar with the matter who spoke on the condition of anonymity to discuss internal deliberations.

The move late last year by Rosen, an appointee of President Trump, angered some career prosecutors in the Justice Department’s Public Integrity Section and has delayed for months the release of an Interior Department Office of Inspector General report about Zinke’s conduct.

At issue is whether Zinke made false statements to Interior investigators who were looking into his decision not to grant a petition by two Indian tribes to operate a commercial casino off reservation land in East Windsor, Conn.

The Mashantucket Pequot and Mohegan tribes’ casino plans had prompted pushback by MGM Resorts International, which operates a gambling facility across the state border in Massachusetts. The tribes’ proposal became a source of contention at Interior and the White House during Trump’s first months in office.

Prosecutors convened a grand jury in February 2019 to examine the matter.

A Justice Department official said that lawyers from the Criminal Division presented the case to Rosen’s office in late 2019 and that “substantial questions arose about the strength of the case.” The official said the division “agreed to do additional work.” Rosen argued that lawyers needed to get more evidence and hone their case for charging Zinke with lying to federal investigators, according to people familiar with the matter.

A person familiar with the matter said the case technically remains open — meaning that when Biden administration officials take over at the Justice Department in January, prosecutors and lower-level officials could again press their case for charges to a potentially more friendly audience. The passage of time, though, generally makes cases weaker as witness memories fade, and there is no guarantee that higher-ups in a new administration would view the facts differently from Rosen. The Washington Post was unable to determine independently the strength of the case against Zinke.

The New York Times first reported Wednesday that Rosen had delayed possibly bringing charges against the former interior secretary.

The Interior Department’s Office of Inspector General cannot release its report about the casino deal until prosecutors reach a decision about the case. Asked about the matter Wednesday, the OIG declined to comment.

The Post first reported in October 2018 that the OIG had referred the matter to Justice Department prosecutors, who convened a grand jury a few weeks after Zinke officially resigned his post Jan. 2, 2019. Zinke had come under scrutiny for a range of matters, including a land deal in his hometown of Whitefish, Mont.; whether he bent government rules to allow his wife to ride in government vehicles; and his decision to have a security detail travel with him on a vacation to Turkey.

Making false statements to federal officials constitutes a crime, but it can be difficult to prove, because it requires prosecutors to show that a person “knowingly and willfully” lied, rather than simply misstated a fact. Were the Justice Department to decide to move forward, Zinke and his lawyers possibly would be given the opportunity to present their own case to top Justice Department officials, who would ultimately decide whether to authorize charges.

Zinke could not be reached to comment Wednesday evening. In January, he told The Post in an interview that he had done nothing inappropriate in connection to the casino deal.

The tribes sought federal approval in early 2017 to operate a gambling facility off reservation land that would give 25 percent of its slot revenue to the state of Connecticut. After initially denying the petition, Trump administration officials changed their position and allowed the tribes to amend their gambling agreement with the state. MGM, which operates a casino 12 miles away from the planned site, is challenging the federal decision in court. The casino is still in the midst of the zoning process.

“The Department of Interior should not take a position on any activity outside the reservation that is not bound by law or treaty,” Zinke said.

“I sided with a principle that I didn’t want to take a position on something that was off the reservation. I had multiple legal counselors’ opinions about what was legal. The investigators may not have liked my answers, but they were truthful,” he said.