The U.S. Department of Justice is investigating whether President Donald Trump's former Interior Secretary, Ryan Zinke, lied to Department of Interior investigators in what could be a potential criminal violation, the Washington Post reported on Thursday.

The Post, citing three people familiar with the matter, said the former Cabinet official was the center of two probes by his department's inspector general: one involving his real estate transactions in Montana and another over his role in a review of a Connecticut casino project proposed by Native American tribes.

Zinke left the administration on Wednesday but had made no public mention of the ethics investigations upon his departure from Interior, which oversees America's vast public lands. Trump did not give a reason for the departure when he announced it last month.