PHILADELPHIA (AP) - A fired Philadelphia police officer has been charged with murder in the shooting of a fleeing 12-year-old boy, who prosecutors said Monday was on the ground and unarmed when the officer fired the fatal shot.

Philadelphia District Attorney Larry Krasner announced first- and third-degree murder charges against former Officer Edsaul Mendoza in the shooting of Thomas “T.J.” Siderio on March 1, saying video showed to the grand jury contradicts the officer’s version of events. Police say the youth had first fired a shot at an unmarked police car, injuring one of four plainclothes officers inside.

Mendoza, 26, was also charged with voluntary manslaughter and other charges, according to a grand jury presentment unsealed Monday. He had been suspended from his job March 8 with intent to fire.

Court records show Mendoza surrendered Sunday and was denied bail, rare treatment for former law enforcement officers facing charges.

A spokesperson for the Fraternal Order of Police Lodge 5 said the union plans to provide an attorney for the officer.

Court records showed the public defender’s office represented Mendoza at his bail hearing Monday. The defender’s association declined to comment on the case.

New details were revealed in the grand jury documents, including that Siderio had thrown a gun down about 40 feet before he was shot and that he had dropped to the ground, either tripping or obeying a command to get down.

Krasner said the officer crossed between two parked cars and, from about half a car length away, fired the fatal shot from the sidewalk behind the youth.

Krasner said much of the evidence was based on the video, which has not been publicly released. According to grand jury documents, prosecutors created a composite video from two cameras, one that recorded clear visuals of the foot chase and another that recorded a different visual angle but caught sound.

“It is certain that (Siderio) had stopped running and he was possibly surrendering … and he was essentially facedown on the sidewalk,” Krasner said, saying the youth was in a pushup position looking back toward the officer when he was shot.

Krasner called the entire foot chase “tactically unsound” and said the video was “disturbing and very difficult to watch.”

There is no indication that race was a factor in the shooting of Siderio, who was white.