In closing the case, the department brought to an end a long-running investigation into a high-profile shooting that helped galvanise the Black Lives Matter movement and that became part of the national dialogue about police use of force against minorities, including children. The decision, revealed in a lengthy statement, does not condone the officers' actions but rather says the cumulative evidence was not enough to support a federal criminal civil rights prosecution.

Tamir was playing with a pellet gun outside a recreation centre in Cleveland on November 22, 2014, when he was shot and killed by Officer Timothy Loehmann, who is white, seconds after Loehmann and his partner, Officer Frank Garmback, arrived at the scene. The officers were called to the recreation centre after a man drinking beer and waiting for a bus had called 911 to report that a "guy" was pointing a gun at people. The caller told a 911 dispatcher that it was probably a juvenile and the gun might be "fake," though that information was never relayed to the officers.

To bring federal civil rights charges in cases like these, the Justice Department must prove that an officer's actions wllfully broke the law rather than being the result of a mistake, negligence or bad judgement. It has been a consistently tough burden for federal prosecutors to meet across both Democratic and Republican administrations, with the Justice Department declining criminal charges against police officers in other high-profile cases in recent years, including in the deaths of Eric Garner in New York City and Michael Brown in Ferguson, Missouri.

In a statement, Subodh Chandra, an attorney for the boy's family, said the Justice Department's "process was tainted" and the family has demanded prosecutors provide additional information about recommendations made during the probe.

"It's beyond comprehension that the Department couldn't recognise that an officer who claims he shouted commands when the patrol car's window was closed and it was a winter day is lying," Chandra said. "The Rice family has been cheated of a fair process yet again."

In this case, the Justice Department said poor-quality surveillance video recorded in the area where the shooting took place prevented prosecutors from being able to conclusively determine whether Rice was or was not reaching for his toy gun just prior to being shot. The two officers who were investigated told authorities soon after the shooting that Rice was reaching for his toy weapon prior to being shot and was given multiple commands to show his hands.

But the video reviewed by federal prosecutors makes the sequence of events less clear. The grainy time-lapse video, which has no audio, "does not show detail or perspective" and the camera's view is obstructed by a police patrol car, prosecutors said.

In a statement at the scene to three other law enforcement officers, Loehmann "repeatedly and consistently stated" that Tamir was reaching for a gun before he shot him, prosecutors said.

Both Loehmann and Garmback also said in statements after the shooting that Loehmann had given Tamir "multiple commands to show his hands before shooting" and both officers saw him reaching for the weapon. Prosecutors said Loehmann and Garmback were the only two witnesses in the "near vicinity of the shooting."

A state grand jury had declined to indict Loehmann, though he was later fired after it was discovered he was previously deemed "unfit for duty."

Australian Associated Press