WASHINGTON (AP) — Attorney General Merrick Garland is expected to announce that the Justice Department is opening a sweeping investigation into policing practices in Minneapolis a day after a former officer was convicted in the killing of George Floyd.

Wednesday's announcement comes after former officer Derek Chauvin was found guilty of murder and manslaughter in Floyd's death last May, setting off a wave of relief but also sadness across the country. The Black man's death prompted months of mass protests against policing in the U.S.

The Justice Department is already investigating whether Chauvin and the other officers involved in Floyd's death violated his civil rights. The investigation being announced Wednesday is known as a “pattern or practice" and will be a more sweeping probe of the entire department and may result in major changes to policing there, a person familiar with the matter told The Associated Press. The person had direct knowledge of the matter but was not authorized to speak publicly about the upcoming announcement, planned for Wednesday morning.

The investigation will examine practices used by police, including the use of force, and whether the department engages in discriminatory practices, according to the person. It will also look into the department’s handling of misconduct allegations among other things, the person said. It’s unclear whether the years under investigation will begin when Floyd died or before.

The Justice Department had no comment.

Floyd, 46, was arrested on suspicion of passing a counterfeit $20 bill for a pack of cigarettes at a corner market. He panicked, pleaded that he was claustrophobic and struggled with police when they tried to put him in a squad car. They put him on the ground instead.

The centerpiece of the case was bystander video of Floyd, handcuffed behind his back, gasping repeatedly, “I can’t breathe,” and onlookers yelling at Chauvin to stop as the officer pressed his knee on or close to Floyd’s neck for what authorities say was about 9 1/2 minutes, including several minutes after Floyd’s breathing had stopped and he had no pulse.

Floyd's death May 25 became a flashpoint in the national conversation about the deaths of Black Americans at the hands of law enforcement and sparked worldwide protests.

At trial, Chauvin's defense attorney persistently suggested Chauvin’s knee wasn’t on Floyd’s neck for as long as prosecutors argued, suggesting instead it was across Floyd’s back, shoulder blades and arm.

The decision to announce a sweeping Justice Department investigation comes as President Joe Biden has promised his administration would not rest following the jury's verdict in the case. In a Tuesday evening speech, he said much more needed to be done.

“‘I can’t breathe.’ Those were George Floyd’s last words,” Biden said. “We can’t let those words die with him. We have to keep hearing those words. We must not turn away. We can’t turn away.”

The Justice Department had previously considered opening a pattern or practice investigation into the police department soon after Floyd’s death, but then-Attorney General Bill Barr was hesitant to do so at the time, fearing that it could cause further divisions in law enforcement amid widespread protests and civil unrest, three people familiar with the matter told the AP.

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Forliti contributed to this report from Minneapolis.