The US Department of Justice will not bring federal charges against six Baltimore police officers involved in the arrest and death of Freddie Gray.

The six officers were initially charged by Maryland prosecutors after Gray's neck was broken in the back of a police transport van in April 2015. The 25-year-old black man was handcuffed and shackled during the transport but was not wearing a seat belt.

Gray died one week after his arrest. An autopsy revealed Gray died of a "high-energy injury" that likely occurred when the van suddenly slowed down, USA Today reported.

His death prompted weeks of protests and unrest in Baltimore, The Associated Press noted.

Three of the officers were acquitted of their charges at trial. Marilyn Mosby, the State's Attorney for Baltimore, dropped the remaining three state cases.

Bill Murphy, the Gray family's attorney, said the Justice Department told him Tuesday (12 September) that no charges would be filed against the officers.

In September 2015, Gray's family accepted a $6.4m (£4.8m) wrongful death settlement from the city of Baltimore. At the time, Murphy said the settlement "represents civil justice" claiming it would have a calming effect on the city.

The Justice Department had been investigating whether the officers violated Gray's civil rights during the events leading up to his death, The Hill reported.

Five of the officers face internal disciplinary trials, which are scheduled to begin on 30 October.