BALTIMORE >> U.S. Attorney General Loretta Lynch plans to launch a full-scale civil rights investigation into use of force by Baltimore police officers, according to sources with knowledge of the matter.

The decision came as local officials pressed the Department of Justice to launch an inquiry similar to investigations into police departments in Ferguson, Mo., and Cleveland, examining whether officers engaged in patterns of excessive force. In both of those cities, unrest erupted after unarmed people were killed by police.

Lynch visited Baltimore this week and met the family of Freddie Gray, the man who died last month of a severed spine and other injuries sustained while in police custody. Lynch said earlier this week that the Justice Department might need to go beyond a voluntary, collaborative review of use of force by city police that began in October.

“Although the city has made significant strides in their collaborative reform efforts with the Community Oriented Policing Services Office, I have not ruled out the possibility that more may need to be done,” Lynch said earlier this week.

An announcement of the broader investigation is expected Friday, according to a law enforcement official who requested anonymity because the decision had not been made public.

Such civil rights probes examine whether police departments have a history of discrimination or using force beyond standard guidelines, and can lead to years of court monitoring.

The Justice Department’s civil rights division has launched civil rights investigations into 20 police departments in the past six years. They examine excessive force, discriminatory harassment, false arrests, and unlawful stops, searches or arrests.

Baltimore Mayor Stephanie Rawlings-Blake and Sen. Barbara A. Mikulski, D-Md., were among those urging Lynch to launch an investigation.

“In many cities throughout the country, including my own city of Baltimore, the trust between community and police is broken,” Mikulski told Lynch at a Senate committee hearing Thursday. “We must do all we can to restore that trust. We need criminal justice reform undertaken with the fierce urgency of now.”

Other Democratic lawmakers from Maryland sent a letter to Lynch expressing their support for a review. Sen. Ben Cardin and Reps. Elijah E. Cummings, John Delaney, Donna F. Edwards, Steny Hoyer, C.A. Dutch Ruppersberger, John Sarbanes and Chris Van Hollen signed the letter.

“Such an investigation could address issues such as allegations of persistent patterns of police misconduct, use of excessive force, discriminatory policing or use of profiling, and improper stops, searches, or arrests,” they wrote. “We would welcome a detailed report on the BPD along with recommendations to reform this critical agency in a timely manner.”

Before receiving word that Lynch planned to proceed with an investigation, police Commissioner Anthony W. Batts welcomed calls for a more in-depth review “with open arms.” He also noted that the department had made significant steps toward reducing complaints of violence against its officers.

“We have never shied away from scrutiny or assistance,” Batts said in a statement. “Our work is ongoing, and anyone who wishes to be a part of helping the department better connect with the community will always be welcome.”

The city is already undertaking a voluntary collaborative project with the Justice Department and until Wednesday, Rawlings-Blake had resisted calls for a higher-level “pattern or practice” review.

The collaborative review began in October after The Baltimore Sun reported that the city has paid $5.7 million in 102 court judgments and settlements for alleged police misconduct since 2011. Nearly all of the people who received payouts were cleared of criminal charges.