The Justice Department on Thursday said it was launching a widespread probe into the police force in Phoenix to examine whether officers have been using excessive force and abusing people experiencing homelessness.

The investigation into the City of Phoenix and the Phoenix Police Department is the third sweeping civil investigation into a law enforcement agency brought by the Justice Department in the Biden administration and comes as the department has worked to shift its priorities to focus on policing and civil rights. Few such investigations were opened during the Trump administration.

Attorney General Merrick Garland said the probe will also examine whether police have engaged in discriminatory policing practices and will work to determine if officers have retaliated against people engaged in protected First Amendment activities.

In June, the top prosecutor in Maricopa County, which includes Phoenix, permanently dismissed charges that included gang allegations against more than a dozen people arrested at an October 2020 protest against police brutality.

The move came amid complaints from civil rights advocates that Phoenix police and prosecutors were pursuing gang charges as part of abusive political prosecutions intended to silence dissent and scare protesters.

Phoenix Mayor Kate Gallego, a Democrat, hailed the Justice Department investigation and said it will help with ongoing police reform measures she has been pushing since taking office in 2019.

“Public safety reform is an ongoing process in Phoenix, and now, with the help of the USDOJ, this robust program will continue,” Gallego said in a statement.

The city also plans to start a new program this year to respond to mental health calls by placing behavioral health professionals in the field. The city also has a new office of police accountability that is charged with independently investigating allegations of wrongdoing by officers.

That office may be hamstrung, however, by a new state law signed by Republican Gov. Doug Ducey that limits civilian review boards like the one Phoenix has set up.

City Councilman Sal DiCiccio, a frequent defender of Phoenix police, said the department ”has been under extreme attack by activists bent on defunding the police.”

“I welcome another set of eyes to see what we already know: that we have a department staffed by dedicated individuals who go to great lengths to protect our community, and do so honorably and fairly,” he said in a statement.

The American Civil Liberties Union of Arizona, which has sued Phoenix police in the past for actions against protesters, said the investigation was needed to force the department to change.

“This is not a case of a few bad apples – Phoenix PD has deep-rooted, systemic problems with the way it treats community members,” Victoria Lopez, the group’s advocacy and legal director, said in a statement.

Part of the investigation will also examine whether police officers have been violating the rights of people who are experiencing homelessness by “seizing and disposing of their belongings in a manner that violates the Constitution,” Garland said.

The new investigation is known as a “pattern or practice” — examining whether there is a pattern or practice of unconstitutional or unlawful policing — and is generally is a sweeping review of the entire police department.

In announcing the probe, Garland also pointed to what he described as “straining the policing profession by turning to law enforcement to address a wide array of social problems.”

“Too often we asked law enforcement officers to be the first and last option for addressing issues that should not be handled by our criminal justice system,” he said “This makes police officers’ jobs more difficult, increases unnecessary confrontations with law enforcement and hinders public safety.”

Assistant Attorney General Kristen Clarke said investigators will meet with police officers and supervisors, review body camera video, along with training materials and other records. She said the Justice Department spoke with Phoenix city officials and they had expressed support for the probe.

“Protecting the rule of law demands that those who enforce our laws also abide by them,” Clarke said.

The Justice Department had reviewed an array of publicly available information, including lawsuits and news reports before it decided to open the Phoenix investigation, Clarke said.

The police force has come under fire in recent years for its handling of protests and the high number of shootings. One lawsuit alleged that police and prosecutors colluded to target protesters during a demonstration last summer. In February, a local television station reported that a team of police officers had celebrated shooting a protester in the groin during another protest with commemorative coins they would share.

“We found that the evidence here warrants a full investigation, but we approach this process with no predispositions or pre-drawn conclusions,” Clarke said.

Phoenix Police Chief Jeri Williams defended the department and the reforms it has made in recent years at a news briefing. But she said she is open to any Justice Department recommendations.

“The Department of Justice inquiry is another opportunity to further improve the department and to better serve our city,” Williams said. “Wearing the badge is a privilege, not a right. I’ll say that again, wearing this badge is a privilege, not a right.”

“The majority of our officers out there act every day with professionalism and compassion,” she added.

Earlier this year, the Justice Department announced it was opening similar investigation into police forces in Minneapolis, after the death of George Floyd, and in Louisville, Kentucky, after the death of Breonna Taylor.