CHICAGO — Eddie Johnson, who took over Chicago’s police department at a time of cratering public confidence and a spike in homicides, announced on Thursday that he would retire, saying at an emotional news conference that after 31 years of police work, “it’s time.”
Superintendent Johnson, a native of Chicago who spent his entire career in the department, stabilized a city and a police force that were in crisis after the 2014 killing of Laquan McDonald, a black teenager who was shot 16 times by a white officer.
With his family and Mayor Lori Lightfoot at his side, Superintendent Johnson said that he worked to overhaul a department whose institutional failures he had witnessed since he grew up in the Cabrini-Green public housing projects.
“Like too many children in Chicago, I experienced the trauma of gun violence firsthand as a child,” he said. “I saw how these unspeakable acts could tear a family apart. I also saw how those who were sworn to protect our city instead relied on prejudice and intimidation. I could have easily learned to hate this city. But my family taught us to love it.”
Chicago becomes the latest in a series of large cities this year to experience turnover at the top of their police departments. The Philadelphia police commissioner abruptly resigned in August, the chief in Charlotte, N.C., announced plans to step down, and a new commissioner was appointed this week in New York City.
During more than three years in charge of the Chicago Police, the second-largest municipal police force in the country, Superintendent Johnson led an overhaul in training, introduced more restrictive rules for when officers could use force, and guided the department into a court-enforced consent decree with the Justice Department. After a large rise in homicides early in his tenure, the city’s murder rate has steadily dropped.
But the superintendent faced mounting problems, especially in recent weeks. He requested an investigation of himself last month after being found asleep in a parked S.U.V. late at night. Superintendent Johnson put the blame for the episode on medication, but Mayor Lightfoot later said the superintendent had been drinking on the evening in question. The superintendent then received a vote of no confidence from leaders of the city’s main police union.
Superintendent Johnson, 59, said he would stay on until the end of the year. His departure will leave the city and its new mayor, Ms. Lightfoot, facing difficult choices about what type of leader to select for the department, which has faced distrust from residents and intense criticism over crime levels.
After video of the shooting of Mr. McDonald was released in late 2015, protesters marched for weeks, the city’s top police official was fired, and a national search for a new superintendent ended with a political stalemate. Superintendent Johnson had not applied for the top job, but eventually he was tapped.
Ms. Lightfoot praised Superintendent Johnson on Thursday for his long record of service, for his character, and for defiantly refusing to attend a speech by President Trump at a recent gathering of police chiefs in Chicago.
“Superintendent Johnson showed this city over and over again, but particularly in that act, that he loves this city and will protect our values, no matter what,” she said.
While there hasn’t been an overriding common factor in the recent high-level resignations at large police departments, the portfolio of skills needed to be a successful big-city chief has greatly expanded in recent years, and so has the range of potential problems that can quickly bring a chief down.
“The expectations have never been higher, and every police chief knows that they are one bad car stop away from losing their job,” said Chuck Wexler, a former senior official at the Boston Police Department who is now executive director of the Police Executive Research Forum, a nonprofit group in Washington.
It has become harder to find suitable candidates to fill these jobs, Mr. Wexler said, noting that big-city chiefs now have to be skilled in a wide range of political and technical challenges, including facial recognition technology, preventing police suicides, combating terrorism, dealing with police-involved shootings and, of course, creating public trust.
When Superintendent Johnson took office in 2016, Chicago was in the middle of what would be its deadliest year in two decades, with more than 760 homicides, the most of any American city that year. The violence terrified residents, drew national attention and helped make the city a favorite target of President Trump, who at one point said he would “send in the Feds” to address the city’s “carnage.”
“Chicago will never stop its crime wave with the current Superintendent of Police,” Mr. Trump tweeted last month after Superintendent Johnson chose to skip his speech at the policing conference. “It just won’t happen!”
Though gunfire remains common in Chicago, and more than 420 people have been killed in the city this year, Superintendent Johnson presided over major overall reductions in violence. Through the end of October, there were 2,242 shooting victims in Chicago this year, down from 3,574 during the comparable period in 2016.
Superintendent Johnson also tried to repair his department’s strained relationship with black residents. Tensions reached a nadir after the McDonald shooting video was released. The officer involved in that shooting, Jason Van Dyke, was convicted last year of second-degree murder.
“When I took over in 2016, everything was a mess: Crime was a mess, police morale was a mess, the community didn’t trust the police at all,” Superintendent Johnson told reporters this week as he hinted at retirement. “Are we where want to be? No, we’re not. But I think we’ve made significant progress.”
Richard A. Oppel Jr. contributed reporting from New York.