CLEVELAND » A white Cleveland police officer had no choice but to fatally shoot a 12-year-old black boy carrying a pellet gun, an expert on police use of force said in a report released publicly Thursday by the Cuyahoga County Prosecutor’s Office.

Retired Florida police officer W. Ken Katsaris is the third expert who has concluded that patrolman Timothy Loehmann was justified in shooting Tamir Rice outside a Cleveland recreation center Nov. 22, 2014.

The release of the latest report comes at a time when a county grand jury is hearing evidence from prosecutors to determine whether criminal charges should be filed against Loehmann, who was a rookie a year ago, and his training officer, patrolman Frank Garmback.

"This unquestionably was a tragic loss of life," Katsaris wrote. "But to compound the tragedy by labeling the officers’ conduct as anything but objectively reasonable would also be a tragedy."

Katsaris testified for the prosecution at the trial of white Cleveland patrolman Michael Brelo, who was charged with two counts of voluntary manslaughter for firing the final 15-rounds of a 137-shot barrage that killed two unarmed, black people at the end of a high-speed chase three years ago. A judge acquitted Brelo of the charges in May.

Attorneys for the family of Tamir Rice have been incensed by the release of the expert reports and have called for Cuyahoga County Prosecutor Tim McGinty to step aside and allow a special prosecutor to take over the case. The attorneys have said the experts, including Katsaris, are clearly biased in favor of police.

"Regrettably, with the release of yet another utterly biased and shamelessly misguided ‘expert report’ the County Prosecutor is making clear his intention to protect the police from accountability under the criminal laws, rather than diligently prosecute them," attorney Jonathan Abady of New York said in a statement Thursday.

McGinty said his office hasn’t reached any conclusions about the case or what recommendation he will make to the grand jury.

"It would be premature for me to announce any final decision on charging," he said in a statement.

McGinty has come under fire for his recent remarks that the Rice family has "economic motives" in their continued calls for justice. The boy’s mother, Samaria Rice, has a federal lawsuit pending against the two officers and the city of Cleveland. A group of rabbis and ministers earlier Thursday called for activists to continue "nonviolent actions" if McGinty refuses to relinquish the case.

The deaths of Tamir Rice and other black males at the hands of police in other cities have sparked outrage and the creation of the national Black Lives Matter protest movement. Tamir’s death has drawn an especially strong response because of grainy, choppy footage from a surveillance camera that shows the boy being shot by Loehmann within two seconds of a cruiser skidding to a stop near the boy. McGinty on Thursday released more footage of the shooting captured at a different angle farther away.

Police officials said initially that Loehmann yelled three times at Tamir to raise his hands. Investigators from the county sheriff’s office said there was no proof that Loehmann said anything to the boy. The officers had responded to a 911 call reporting that a man was pulling a gun in and out of his pants and was pointing it at people. The caller also said the gun might not be real and that the man might be a teenager.

Katsaris said in his report that while that information should have been passed on to the officers, it’s ultimately not relevant.

"It is simply obvious that the officers had a reasonable belief that Rice was armed," Katsaris wrote.

AP reporter Andrew Welsh-Huggins in Columbus contributed to this report.