WASHINGTON (Reuters) - United States Attorney General Loretta Lynch will launch a federal probe into whether Baltimore's police department has engaged in a "pattern or practice" of excessive force, the Washington Post reported on Thursday.
The Post, citing two law enforcement officials, said Ms Lynch's announcement of the investigation could come as soon as Friday.
Baltimore Mayor Stephanie Rawlings-Blake asked the US Justice Department on Wednesday to investigate the city's police department for civil rights violations after the death of a black man from injuries sustained in police custody.
The investigation will look into police practices such as frisks, street stops of suspects and arrests to see if they violate the US Constitution, Ms Rawlings-Blake said at a news conference.
The request follows the April 19 death of Freddie Gray, 25, who sustained spinal injuries after being arrested. His death sparked protests and a day of arson and looting in the largely black city.
Maryland Governor Larry Hogan lifted a state of emergency for Baltimore on Wednesday. "We cannot be timid in addressing this problem and I am a mayor that does not shy away from our city's big challenges," Ms Rawlings-Blake said.
Six officers were charged last week in the case, which involves the latest in a series of US deaths of unarmed black men involving police officers.
The mayor said the city would seek to have its 3,200-member police department equipped with body cameras by the end of the year. Advocates see cameras as a way to monitor police encounters with civilians.
Ms Lynch met the mayor, police officials and community leaders on Tuesday.
Ms Rawlings-Blake, a Democrat who took office in 2010, said the request was part of her years-long effort to reform police.
She said the department had made progress, with complaints last year of excessive force down by 46 percent. But improvements had not gone far enough, Rawlings-Blake said.
Mr Gray's death provoked a day of rioting on April 27 in which a number of businesses were looted and a CVS Health Corp location was burned. The pharmacy chain said on Wednesday that it would rebuild the store.
The Justice Department has conducted similar reviews of US police departments. An investigation of police in Ferguson, Missouri, where an officer shot dead an unarmed black teenager last year, concluded in March that the department routinely engaged in racially biased practices.
The Justice Department is investigating possible civil rights violations in Gray's death.
Last October, officials in Baltimore asked the Justice Department to begin an informal collaborative review of the city's police department after the Baltimore Sun reported that Baltimore had paid almost US$6 million (S$8 million) since 2011 to settle lawsuits alleging police brutality and other misconduct.
The American Civil Liberties Union said on Wednesday that it had requested information about surveillance flights over Baltimore by the Federal Bureau of Investigation (FBI) and other agencies that it said may have improperly surveilled and targeted the public.
The FBI did not immediately respond to a request for comment on the ACLU statement.