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The U.S. Justice Department opened a civil rights investigation Tuesday into the death of Freddie Gray amid ongoing protests over the Baltimore man whose spine was allegedly severed while he was in police custody.

Gray, 25, died Sunday, a week after he was arrested April 12 on a weapons charge in Baltimore. The arrest was recorded on cellphone video, which shows Gray being pinned to the ground and then bundled into a police van. He is heard screaming on the video.

After the probe was announced hundreds of protesters again gathered for a rally at the site of Gray's arrest. Holding signs reading "Black Lives Matter" and "No Justice, No Peace," the protesters marched to a nearby police station.

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Baltimore City Police Commissioner Anthony Batts said he was pleased the protest remained peaceful.

"I think that they're sharing their thoughts, they're sharing their concerns and I hear them and I understand," he told NBC affiliate WBAL of the protesters. "And, if I was a parent and that was my child that I lost, I'd be concerned and I'd want to know and want to react."

Protesters have expressed frustrations over how the officers involved had been suspended instead of charged. Batts told WBAL that his detectives are interviewing new witnesses and re-interviewing existing witnesses.

"Our job is also to have balance and not to rush to a conclusion, and that's why the direction right now is get the evidence and make sure it's right because we're only going to have one chance at this," he told WBAL.

Deputy Police Commissioner Jerry Rodriguez earlier told NBC station WBAL that the department is fully cooperating with the investigation and is handing over documents.

IN-DEPTH

— M. Alex Johnson