The Justice Department said on Thursday that it had begun a sweeping civil rights investigation into policing in Memphis, digging into allegations of pervasive problems with excessive force and unlawful stops of Black residents that were amplified by the fatal beating of Tyre Nichols in January.

In announcing the investigation, officials specifically cited Mr. Nichols, a 29-year-old Black man who died after a traffic stop escalated into a brutal confrontation in which Memphis police officers kicked, pepper-sprayed and pummeled him, even as he was restrained, and then failed to render aid.

The beating, which was captured by body camera and surveillance footage, brought intense scrutiny onto how the Memphis Police Department operates. Residents and activists argued that Mr. Nichols’s case was anything but an isolated episode and was instead reflective of an aggressive approach that officers routinely took with Black people — particularly officers from specialized units patrolling high-crime areas, like those who stopped Mr. Nichols.

A preliminary review by the Justice Department lent credence to those claims, officials said.

“We received multiple reports of officers escalating encounters with community members resulting in excessive force,” Kristen Clarke, the assistant attorney general for the Civil Rights Division of the Justice Department, said in a news conference on Thursday in Memphis. “There are also indications officers may use force punitively when faced with behavior they perceive as insolent.”

The investigation is the ninth so-called pattern or practice inquiry that has been pursued by the Biden administration, following in the mold of other sprawling inquiries that were started across the country after high-profile cases of deadly police violence, including in Minneapolis after the death of George Floyd and in Louisville, Ky., after the fatal shooting of Breonna Taylor.

These investigations, which can be exhaustive and stretch on for years, often result in searing accounts that detail patterns of misconduct and in court-enforced agreements known as consent decrees, which are designed to substantially overhaul police practices and add layers of accountability.

In Memphis, officials said the preliminary review revealed instances beyond Mr. Nichols’s case of officers using force against people who were already restrained or in custody. “At times, the use-of-force practices results in serious physical injuries,” Ms. Clarke said.

The review also found evidence suggesting unlawful stops, searches and arrests, and racial discrimination in street enforcement.

City officials vowed on Thursday to cooperate with the investigation. “The city will be a good partner in this new inquiry,” Jim Strickland, Memphis’s mayor, said in a statement, adding that the city had already been “transparent and cooperative” in other police accountability efforts.

But Mr. Stickland objected to the Justice Department’s deciding to proceed with an investigation without first having more discussions with city officials. “I know they discussed the need for such an action with many other individuals,” he said. “I hope the remainder of the process is more forthright and inclusive than it has been so far.”

Chief Cerelyn J. Davis of the Memphis Police Department said she was committed to forging a better relationship with the community and holding officers accountable, yet also argued that Mr. Nichols’s case was not representative of the department as a whole.

“As we have said all along, all M.P.D. officers are expected to act in accordance with their oath of office, their training and department policies at all times,” Chief Davis said in a statement. “While the officers involved in the Tyre Nichols case demonstrated no regard for these tenets, I am appreciative of the M.P.D. officers that continue to serve our city with integrity.”

Federal officials said the civil rights investigation was separate from a continuing criminal investigation related to Mr. Nichols’s death. Five Memphis police officers have already been charged in state court with second-degree murder in connection with the fatal beating. All have pleaded not guilty to those charges.

Mr. Nichols’s death reverberated far beyond Memphis, with much of the outcry fueled by the violence captured in the videos that the city released to the public.

Mr. Nichols was stopped on Jan. 7 by officers from a specialized group known as the Scorpion unit, which had been created by Chief Davis to aggressively patrol areas where violence and crime were persistent. Officers claimed that they had stopped Mr. Nicholas for reckless driving, but police officials later acknowledged that they could find no evidence to justify the stop.

“The family of Tyre Nichols is grateful that the Department of Justice heard their cries for accountability and are opening this investigation,” lawyers representing the family said in a statement on Thursday. “Actions such as this will continue to show that the federal government will not let corruption within police departments take the lives of innocent Americans.”