The Justice Department announced on Thursday the results of a yearslong investigation that found Phoenix police had used excessive force and discriminatory policing against Black, Hispanic and Native American people.

The findings came in a 126-page report, that said the Phoenix police department committed constitutional and statutory violations in all five areas investigated: excessive use of force, discriminatory and retaliatory policing, and its treatment of the homeless and disabled people..

“The Justice Department has concluded there is reasonable cause to believe that the City of Phoenix and the Phoenix Police Department engage in a pattern or practice of conduct that deprives its residents and visitors, including Black, Hispanic and Native American people, of their rights under the Constitution and federal law,” Attorney General Merrick B. Garland said in a statement.

City officials say they have put reforms in place since the investigation was launched in 2021.

Unlike in other federal investigations of city police, no single incident kicked off the Biden administration review, which covered the years between 2019 and 2022. But Phoenix had the highest number of fatal police shootings in the country in 2018, resulting in 23 deaths, and critics cite a history of mistreatment of minorities and disabled and homeless people.

The Justice Department said it wants to work with Phoenix to put reforms in place, even though city officials have indicated they do not want the federal involvement. That could potentially provoke a fraught confrontation between the Biden administration and the largest city in a pivotal swing state. Last month, former President Donald J. Trump, the presumed Republican candidate, appeared to have an edge in the state, according to a poll of registered voters. President Biden narrowly won Arizona in the 2020 election.

This is a developing story and will be updated.