Federal Emergency Management chief Brock Long and two top aides have been referred to prosecutors for violation of "criminal statues," The Wall Street Journal reported Monday.
The case was sent to federal prosecutors, who will uncover whether to issue criminal charges, those familiar with the probe said.
Long and two other federal employees may have broken several laws while going back and forth between Washington, D.C. and Long's home in Hickory, N.C. at taxpayers' expense.
Long says he will cooperate with investigators. In the past, the investigation was led by the Department of Homeland Security's inspector general before it was handed over to federal prosecutors.
Long joins a score of Trump aides found to have used taxpayer dollars to fund their lifestyle. Most notably was former EPA chief Scott Pruitt, who was forced to resign after it was discovered he made strange purchases and used secret service to run errands for him.
When President Donald Trump campaigned in 2016, he pledged to "drain the swamp" of unethical political leaders in Washington.