PHILADELPHIA — The family of a 12-year-old boy who was fatally shot by a Philadelphia police officer three years ago has agreed to a $3 million settlement with the city.

Thomas “T.J.” Siderio was on the ground and unarmed when the officer, Edsaul Mendoza, fired the fatal shot into his back, authorities have said. The youth had first fired a shot at an unmarked police car, injuring one of four plainclothes officers inside, and he eventually threw a gun down about 40 feet (12 meters) during a foot chase before he was shot and then either tripped or dropped to the ground.

Mendoza, a five-year veteran of the force who was fired a week after the shooting in 2022, pleaded guilty to third-degree murder in April 2024. He was sentenced to eight to 20 years in prison.

“This is a tragic case that never should have happened,” Michael Budner, a partner at Saltz Mongeluzzi Bendesky, one of two law firms that represented the family. “This resolution provides some measure of justice to the family of TJ Siderio for their devastating loss.”

Police officials have said the undercover officers had been looking for a teenager they wanted to talk with about a firearm investigation. They saw Siderio and an unnamed 17-year-old and maneuvered the car around the block and next to them to initiate a stop.

Prosecutors said that almost at the same time the officers turned their red and blue lights on, a shot came through the back passenger window and ricocheted around the car. One officer was treated for injuries to his eye and face caused by broken glass.

Mendoza and another officer on the passenger side got out and fired one shot each, according to police. Mendoza then chased Siderio down the block, firing twice and striking the boy once in the back in what prosecutors say was “relatively close range.”