A grand jury has declined to indict two Cleveland police officers involved in the fatal shooting of Tamir Rice.
Cuyahoga County Prosecutor Timothy McGinty announced the decision Monday afternoon, after presenting evidence to the panel since October.
"Based on the evidence they heard and the law as it applies to police use of deadly force, the grand jury declined to bring criminal charges," McGinty said.
Officer Timothy Loehmann shot the 12-year-old Nov. 22, 2014, at Cudell Recreation Center, where a 911 caller had reported seeing "a guy with a gun."
The witness told dispatchers the gun was "probably fake," but that information was not passed along to officers responding to the call.
McGinty described the boy's death as "an absolute tragedy" caused by a "perfect storm of human error" -- but he said prosecutors were unable to prove the officers acted unlawfully.
Officer Frank Garmback stopped the patrol car next to a gazebo where Tamir had been sitting, and both officers jumped out of the vehicle.
The officers said the boy ignored repeated commands to drop the weapon, but video recorded by nearby surveillance cameras shows Loehmann open fire almost instantly after he got out of the car.
McGinty said the grainy surveillance video was enhanced by analysts who work with federal investigators, and he said this video shows the boy reaching into his waistband for the air pellet gun.
The prosecutor said Tamir was likely trying to hand over the toy weapon or show the officers the gun was not real, but he said it "would be unreasonable to expect officers not to shoot until they determined whether gun is real."
"Believing he was about to be shot was a mistaken but reasonable belief," McGinty said.
The prosecutor suggested that charges against the officers would have been unjust and possibly violate his own professional ethics.
"We don't second-guess police officers," he said. "It's clear the officers were not criminal."
The officer shot Tamir once in the stomach, and the surveillance video shows the officers standing beside him for several minutes without rendering aid.
Police stopped the boy's sister from coming to his aid and forced her to watch her brother lie bleeding from the inside of their patrol car.
Tamir died the following day.
Prosecutors showed video of Tamir, who they described as looking like an adult, walking around the park pointing the gun as he played shortly before he was shot.
Ohio law permits the open carry of firearms.
McGinty called on toy manufacturers to stop making realistic-looking toy weapons, and he expressed hope that body cameras worn by officers would help restore public confidence in police.
Watch live video of the announcement posted online by WKYC-TV: