The announcement came a day after city officials promised an open and transparent investigation into the death of Gray, 25, who was arrested on a Baltimore street on April 12 and died Sunday. An autopsy released Monday showed that Gray died from a severed spine.
The death of the black man at the hands of the police has sparked peaceful protests in the city. Civil rights leaders have called for a federal inquiry, as have some members of Congress.
"The Department of Justice has been monitoring the developments in Baltimore ... regarding the death of Freddie Gray," Justice Department spokeswoman Dena Iverson said in a statement emailed to reporters. "Based on preliminary information, the Department of Justice has officially opened this matter and is gathering information to determine whether any prosecutable civil rights violation occurred."
There was no indication how long the department would take with its investigation, which could lead to federal charges. Baltimore police said they expected to report the findings of their investigation to local prosecutors by May 1.
At a news conference Monday, authorities said the autopsy showed that Gray had died of significant spinal injury, but there was no indication of how he was injured.
Gray spotted Baltimore police officers April 12 and then fled, along with another man, authorities said. The lawyer for Gray's family has told reporters that he doubted police had any reason to stop or chase Gray.
According to video released by the city, Gray was arrested and placed in a police van. But there is no video of what happened inside the vehicle, police said.
Once inside the van, Gray became "irate," according to police, and was placed in leg irons. Gray asked for medical care several times en route to the police station, but the van made several stops along the way, including to pick up another prisoner in an unrelated case, police said.
Gray was eventually charged with carrying a knife, which police discovered in his pocket after the arrest, according to the charging papers filed by Officer Garrett Miller.
Miller is one of the six officers who have been suspended with pay during the investigation, police announced. The officers' time on the force ranges from three years to 18 years, police said.
According to city officials, the other suspended officers are: Lt. Brian Rice, 41, who has been with the department since 1997; Sgt. Alicia White, 30, with the department since 2010; Officer Caesar Goodson, 45, who has been there since 1999; and Officers William Porter and Edward Nero, who along with Miller, joined in 2012.
Mayor Stephanie Rawlings-Blake and Police Commissioner Anthony W. Batts called for calm to allow police to complete their investigation. On Monday, Rawlings-Blake said that city officials had sought help from the U.S. Justice Department to study police policies and procedures.
Batts said he had ordered his department to rewrite the rules on moving suspects and on how to respond to medical emergencies.
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