President Donald Trump’s former personal physician Rear Adm. Ronny Jackson is being investigated by the Pentagon’s Office of Inspector General following accusations of unprofessional behavior.

Jackson’s nomination as Veterans Affairs secretary was withdrawn in April amid allegations of crashing a government car after drinking, giving out unprescribed sleeping pills and being drunk on duty during foreign work travel. These instances were brought to light by Sen. Jon Tester (D–Mont.) during the confirmation process.

Jackson, who served as presidential physician for former Presidents Barack Obama and George W. Bush, denied the allegations and called them “completely false and fabricated” in a statement.

“The DoD Office of Inspector General has initiated an investigation into allegations related to Rear Admiral (Lower Half) Ronny L. Jackson,” Inspector General spokesman Bruce Anderson told CNN in a statement. Anderson did not say whether the investigation is administrative or criminal and declined to identify who was being interviewed, but said the investigation began in the last month, according to CNN.

After Jackson’s nomination was withdrawn in April, the Pentagon issued a statement saying the Inspector General had “received the allegations and is assessing what investigations and reviews have already been conducted related to these issues, any jurisdictional issues that may relate to the allegations, and the scope of the allegations and complaints related to these issues.”

Jackson is still working in the White House Medical Unit as the investigation begins, but is no longer the president’s personal physician. He has reportedly been nominated for a second star, but will need to either be confirmed by the Senate for the second star or be put in for retirement.