CHICAGO (Reuters) - Chicago Mayor Rahm Emanuel on Monday named a veteran black police supervisor to lead the department as he tries to rebuild the third-biggest U.S. city’s trust in a police force facing a federal investigation and racism accusations.

Chicago Mayor Rahm Emanuel (3rd L) announces that he is appointing Eddie Johnson (4th L) as the Interim Superintendent of the Chicago Police Department, during a news conference in Chicago, March 28, 2016. REUTERS/Kamil Krzaczynski

Eddie Johnson, the 55-year-old head of the police department’s patrol division, is the third superintendent to lead the Chicago Police Department in less than four months.

The Democratic mayor said Johnson, who grew up in a city housing project and started as a beat officer, had a strong record of fighting crime in his 27 years on the force and would help rebuild morale among police.

“He has the command, the character and the capability to lead the department at this critical juncture,” said Emanuel, a former chief of staff to President Barack Obama.

The tarnished image of Chicago’s police has been a political liability for Emanuel, who defied calls to resign last year after days of protests over a white officer’s shooting of black teenager Laquan McDonald.

That case was one of numerous fatal police shootings of unarmed African-Americans across the United States that have stirred outrage and raised questions of racial bias in policing.

In picking Johnson, Emanuel rejected recommendations made by a civilian board that had selected three finalists.

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Johnson’s selection answered calls from civic leaders for an African-American veteran of the force to be chosen. He also had the support of a powerful contingent of minority aldermen, which had not endorsed the black finalist from inside the force, local media said.

Johnson, who did not apply for the position, was named to the job on an interim basis, but the appointment is widely expected to be made permanent if his tenure proceeds smoothly.

Johnson said that trust was the key to good policing.

“It is the central challenge facing Chicago today. I know that ... trust has been broken too often, not just in Chicago but across America where abusive police practices have occurred,” he told a news conference.

The law requires Emanuel to pick a candidate recommended by the Chicago Police Board. The board will begin a new search, and Johnson said he would apply.

Their recommended finalists for the job in this round included two African-Americans: Cedric Alexander, DeKalb County, Georgia public safety director, and Eugene Williams, Chicago’s police deputy superintendent. Anne Kirkpatrick, retired Spokane, Washington police chief, is white.

Johnson said he did not apply for the post in support of John Escalante, who was named interim superintendent in December. Escalante replaced Gerry McCarthy, who was ousted amid public outrage that the city delayed for more than a year the release of a video that led to first-degree murder charges against the officer in the McDonald shooting.

In the aftermath of the protests, the U.S. Justice Department launched an investigation into Chicago police shootings.

The three candidates chosen as finalists all had good attributes, but only Johnson met all qualifications, the mayor said without providing details.

Of 405 people shot by Chicago police over the past eight years, 74 percent were black. The city’s population is about one-third black.