Chicago Police Superintendent Eddie Johnson, who had already tendered his resignation but was staying through the Chicago Police Department’s transition of authority, was booted from office Monday by Chicago’s mayor, Lori Lightfoot, after being fired for what she called a series of “ethical lapses” stemming from an incident that occured earlier this year.

Johnson had planned to retire at year’s end, but the firing is effective immediately, according to Lightfoot, who made the announcement Monday morning in a statement issued to local press. Lightfoot cited “ethical lapses” and a series of “intentionally dishonest” statements made by Johnson in the course of an investigation, but gave no specific examples.

On October 17th of this year, Johnson was found slumped behind the wheel of his car at a stop sign near his home on the city’s southwest side. Johnson reportedly told the officers — and later the mayor — that he had just started a new prescription and wasn’t aware that the medicine would make him drowsy. He later admitted to Lightfoot that he may have had “a couple of drinks with dinner” before he got behind the wheel of his car.

The incident led to an Inspector General’s investigation, but Johnson decided to submit his resignation voluntarily before that investigation concluded, and Lightfoot bid Johnson a fond farewell at a press conference last month, praising him for his contributions to the city, and lauding his efforts at reducing crime — and particularly gun crime — in Chicago.

Monday, Lightfoot told a different story.

Upon a thorough review of the materials of the Inspector General’s ongoing investigation, it has become clear that Mr. Johnson engaged in a series of ethical lapses that are intolerable,” the mayor said in her statement. “Mr. Johnson was intentionally dishonest with me and communicated a narrative replete with false statements regarding material aspects of the incident that happened in the early morning hours of October 17.”

“Had I known all the facts at the time, I would have relieved him of his duties as superintendent then and there,” Lightfoot added. She went on to say that Johnson “misled” the people of Chicago with his official story.

Lightfoot refused to give details about Johnson’s ethical failings, out of deference to Johnson’s family, but it does not appear the mayor’s office will stand in the way of the Inspector General if it chooses to make its report public.

Johnson was remarkably successful at lowering the incidents of gun crime in the city, and gun-related violence dropped around 10% two years in a row under his leadership. He was also instrumental in pursuing the case against former “Empire” actor Jussie Smollett, who Chicago officials say lied about being the victim of a racist and homophobic attack in the city’s tony Streeterville neighborhood back in January.

But Johnson has also been a favorite target of President Donald Trump, particularly after he refused an invitation to join Trump at a recent police chiefs conference that took place in Chicago. Trump, who gave the keynote speech at the event, poked fun at Johnson from the podium and criticized Johnson’s inability to put a real lid on the city’s crime, comparing Chicago unfavorably to war zones in the Middle East.

Former Los Angeles Police Chief Charlie Beck was supposed to take over as interim police superintendent once Johnson retired. He started as Johnson’s official replacement Monday morning.