Eddie Johnson, the beleaguered Chicago Police superintendent, is set to announce his retirement later Thursday morning, bringing an end to his three-plus years leading the department -- but also stepping down amid an internal investigation.

Chief Communications Officer Anthony Guglielmi tweeted that Johnson will speak about the matter at 10:45 a.m. ET.

“A true son of Chicago who grew up in public housing & went to public schools went on to become one of our most dedicated public servants,” Guglielmi said. “Chicago Police Supt. Eddie Johnson will announce plans to retire as leader of the nation's second-largest police department.”

Chicago Police Superintendent Eddie Johnson is set to announce his retirement soon. (AP)

CHICAGO MAYOR SPEAKS OUT AFTER JOHNSON FOUND ASLEEP IN CAR

The retirement comes just days after Johnson said he was only considering resigning and amid an investigation into an incident in which officers found Johnson asleep in his car at a stop sign.

"I have given 31 years now to this city, and almost four as superintendent," Johnson said Monday, according to the Chicago Tribune. "You know, but I recognize also that at some point it's time to create another chapter in your life. And I will tell you all this: When my family and I went to London for the Bears game, that's the first vacation like that that I've had since I became superintendent."

He added: "And I looked at my family and it made me realize how much of a sacrifice you make for your family when you take on positions like this."

Mayor Lori Lightfoot recently told the Chicago Sun-Times that Johnson -- following the Oct. 17 sleeping incident -- confessed to her that he had “a couple of drinks with dinner” before getting behind the wheel that night.

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“I know what the superintendent told me, which is that he was…changing medication...He’d been out to dinner with some folks. He told me he was driving home," Lightfoot said to the newspaper. "He felt ill and pulled over to the side of the road, which he believed was the prudent thing to do…[Internal Affairs Divison] will sort out the rest.”

Johnson subsequently requested an investigation of himself.

Fox News' Nicole Darrah contributed to this report.