WASHINGTON, DC - DECEMBER 03:   US Secretary of the Interior Ryan Zinke arrives at the US Capitol prior to the service for former President George H. W. Bush on December 03, 2018 in Washington, DC. A WWII combat veteran, Bush served as a member of Congress from Texas, ambassador to the United Nations, director of the CIA, vice president and 41st president of the United States. A state funeral for Bush will be held in Washington over the next three days, beginning with him lying in state in the U.S. Capitol Rotunda until Wednesday morning. (Photo by Shawn Thew - Pool/Getty Images)
PHOTO: Shawn Thew/Getty Images
WASHINGTON, DC - DECEMBER 03: US Secretary of the Interior Ryan Zinke arrives at the US Capitol prior to the service for former President George H. W. Bush on December 03, 2018 in Washington, DC. A WWII combat veteran, Bush served as a member of Congress from Texas, ambassador to the United Nations, director of the CIA, vice president and 41st president of the United States. A state funeral for Bush will be held in Washington over the next three days, beginning with him lying in state in the U.S. Capitol Rotunda until Wednesday morning. (Photo by Shawn Thew - Pool/Getty Images)
(CNN) —  

Former Interior Secretary Ryan Zinke could be in additional legal trouble despite departing his post, as The Washington Post reported Thursday that he’s being investigated for possibly lying to federal investigators.

According to the Post, three people familiar with the matter said the Justice Department’s public integrity section is looking into whether Zinke lied to Interior Department inspector general investigators. Zinke was the subject of multiple inspector general investigations while head of the Interior Department.

President Donald Trump in December announced Zinke would be leaving the administration at the end of 2018 – just one of several high-profile departures from his team at the end of the year, including the White House chief of staff and defense secretary.

After Trump announced he was leaving, Zinke said in a statement that he was proud of his work as interior secretary and called the allegations against him “false.”

“I love working for the President and am incredibly proud of all the good work we’ve accomplished together,” Zinke wrote on Twitter. “However, after 30 years of public service, I cannot justify spending thousands of dollars defending myself and my family against false allegations.”

The Interior Department IG has opened multiple inquiries into the secretary, including the department’s handling of a Connecticut casino project, whether the boundaries for Grand Staircase-Escalante National Monument were redrawn to benefit a state lawmaker and conversations between Zinke and Halliburton Chairman David Lesar about a land development project in Zinke’s hometown of Whitefish, Montana.

It was during these investigations that investigators became wary that Zinke had lied to them and alerted the DOJ, according to The Washington Post, citing the people familiar with the matter.

A spokesman for Zinke told The Washington Post that Zinke voluntarily participated in the interviews for the probe looking into the Connecticut casino project, and said, according to the paper, “to the best of his knowledge answered all questions truthfully.”

Zinke has previously denied all wrongdoing.

“I follow all rules, procedures, regulations and most importantly the law,” Zinke previously told CNN. “This is another politically driven investigation that has no merit.”

The Justice Department declined to comment to CNN’s inquiry on the matter.

Additionally, Interior Department spokeswoman Heather Swift told CNN that “due to the lapse in appropriations, the Department is unable to respond to inquiries unrelated to shutdown.”

CNN’s Lauren Fox, Gregory Wallace, Ellie Kaufman and Laura Jarrett contributed to this report.