COLUMBUS, Ohio (AP) — While Ohio’s capital city has made significant progress enacting changes to its police department, the city needs additional help because of “fierce opposition” to reform within the agency, city leaders said Wednesday as they requested a Justice Department investigation following a series of police killings of Black people and other controversies.

The request by Mayor Andrew Ginther and City Attorney Zach Klein — both Democrats — capped several painful months for the city, culminating most recently with the April 20 fatal shooting of 16-year-old Ma’Khia Bryant as she swung a knife at a woman. Bryant was Black and the rookie officer who shot her was white.

Criticism has included not just fatal police shootings but also the department’s reaction to last summer’s protests over racial injustice and police brutality following the death of George Floyd at the hands of Minneapolis police officer Derek Chauvin. A report commissioned by city council and released earlier this week criticized both the police department and city leaders, saying Columbus was unprepared for the size and energy of the protests.

“This is not about one particular officer, policy, or incident; rather, this is about reforming the entire institution of policing in Columbus,” Ginther and Klein said in Wednesday’s letter. “Simply put: We need to change the culture of the Columbus Division of Police.”

It’s not unusual for mayors or local law enforcement leaders to ask the Justice Department to review an agency’s record. Those requests sometimes are made when city officials anticipate a federal probe is looming regardless of their wishes.

When the Justice Department does launch such a review, city officials can do little to stop it, so they generally welcome the investigations, at least in public. The mayors of Minneapolis and Louisville, Kentucky, quickly endorsed the reviews the Justice Department recently announced of those cities’ police departments following the killings of Floyd and Breonna Taylor.

It’s likely that the recent police killings in Columbus combined with the mayor’s push for changes would make the city’s request appealing to the Justice Department, said Ayesha Hardaway, a Case Western Reserve University criminal law professor.

“I imagine that Columbus will be considered a good opportunity to make lasting change,” said Hardaway, who has worked with Cleveland’s police department in the wake of Justice Department involvement after the 2014 shooting of 12-year-old Tamir Rice.

A message was left with the Justice Department seeking comment.

The request by Columbus leaders came the same day that the attorney representing the family of Bryant requested a federal investigation into her death and the state’s foster care system.

Columbus remains an outlier among other American cities under Justice Department scrutiny, with multiple initiatives launched over the last few years to address complaints about the police department, pushed by Ginther and the city’s all-Democratic city council.

In 2016, shortly after Ginther took office, the city spent millions of dollars to buy police body cameras for the first time and is now in the process of spending millions more to upgrade them. The city recently created its first-ever civilian review board in a 2020 voter-approved measure pushed by Ginther and the city council.

Despite these efforts, “the City has been met with fierce opposition from leadership within the Columbus Division of Police,” Wednesday’s letter said, which also suggested the Justice Department could use court-ordered measures to force the local police union to comply with changes.

Columbus officers “are always willing to work with any entity to improve policing in the communities they protect and serve,” Jeff Simpson, executive vice president of the local union, said in a statement. “Politicians constantly vilifying officers breeds contempt for authority, emboldens the criminal element and has led to a mass exodus of law enforcement officers from the profession.”

Even with its initiatives, Columbus — the country’s 14th largest city — has recorded a number of contested police shootings.

The most recent cases include Bryant, the April 12 killing of 27-year-old Miles Jackson in a hospital ER room, and 47-year-old Andre Hill. The white police officer who fatally shot Hill Dec. 22 has pleaded not guilty to a number of charges made against him by the state’s attorney general’s office.

The case of Casey Goodson Jr., a 23-year-old Black man who was fatally shot by Franklin County Sheriff’s deputy in early December in Columbus, has widened criticism of policing in the city to include the county sheriff’s office.

In January, interim Columbus Chief Thomas Quinlan was forced out after Ginther said he’d lost confidence in the chief’s ability to make needed changes to the department.

Before the recent police shootings, the city was sued over the 2016 shooting of Henry Green, a Black man, by two undercover white police officers working in an anti-crime summer initiative.

Later in the same year, a white officer fatally shot 13-year-old Tyre King, who was Black, during a robbery investigation. In 2017, a video showed a Columbus officer restraining a Black man lying on the ground and preparing to handcuff him when an officer — Zachary Rosen — who was also involved in the Green shooting arrived and appeared to kick the man in the head.

The city fired Rosen, but an arbitrator ordered him reinstated, angering many in the community while underscoring the challenge that police union contracts can pose for cities trying to hold officers accountable.

Records show that Black residents, about 28% of the Columbus population, accounted for about half of all use-of-force incidents from 2015 through 2019.

The agency — like many big-city departments — is juggling calls for internal change even as it battles street violence. Columbus saw a record 174 homicides in 2020 and has recorded 62 so far this year, a figure not reached until early July of last year.

Federal involvement in the Columbus police department over allegations of officer misconduct isn’t new.

In 1999, the Justice Department sued the city, accusing officers of routinely violating people’s civil rights through illegal searches, false arrests and excessive force. A year later, the government added a racial profiling complaint, alleging that from 1994 to 1999, Black people in Columbus were almost three times as likely as whites to be the subject of traffic stops in which one or more tickets were issued.

A federal judge in 2002 dismissed the lawsuit after the city, which had fought it, made changes on the use of police force and handling of complaints against officers.

In Wednesday’s letter, Ginther pledged to give the Justice Department the city’s full cooperation if the agency agrees to take on the review.

“We want to be partners with the DOJ to bring about meaningful, sustainable and significant reforms,” he wrote. “Not only is the elected leadership in the City of Columbus aligned with this request, but the residents of Columbus unquestionably share the same goal.”