NEW YORK (AP) — After five years of investigations and protests, the New York City Police Department on Monday fired an officer involved in the 2014 chokehold death of Eric Garner, the black man whose dying gasps of “I can’t breathe” gave voice to a national debate over race and police use of force.

Police Commissioner James O’Neill said he fired Daniel Pantaleo, who is white, based on a recent recommendation of a department disciplinary judge.

O’Neill said he thought Pantaleo’s use of the banned chokehold as he wrestled with Garner was a mistake that could have been made by any officer in the heat of an arrest. But it was clear Pantaleo had broken department rules and “can no longer effectively serve as a New York City police officer.”

“None of us can take back our decisions,” O’Neill said, “especially when they lead to the death of another human being.”

The decision was welcomed by activists and Garner’s family, but condemned by the head of the city’s largest police union, who declared that it would undermine morale and cause officers to hesitate to use force for fear they could be fired.

“The job is dead!” Patrolman’s Benevolent Association President Patrick Lynch said at a news conference, standing in front of a police department flag hung upside down.

His voice cracking with anger, Lynch called Pantaleo an “exemplary” officer and called for union members to participate in a no-confidence vote on the mayor and commissioner.

“It’s absolutely essential that the world know that the New York City Police Department is rudderless and frozen,” he said. “The leadership has abandoned ship and left our police officers on the street alone, without backing.”

Pantaleo’s lawyer, Stuart London, said he would use legal appeals to try to get the officer reinstated. He has insisted the officer used a reasonable amount of force and did not mean to hurt Garner.

Mayor Bill De Blasio, speaking at City Hall, said he hoped the decision would let the city, the department and Garner’s family move forward.

“Today, we are finally seeing justice done,” the Democrat said. “Today will not bring Eric Garner back, but I hope it brings some small measure of closure to the Garner family.”

Garner’s death came at a time of a growing public outcry over police killings of unarmed black men, which sparked the national Black Lives Matter movement.

Video of the confrontation between Garner and the officers trying to arrest him for selling untaxed cigarettes drew outrage and was viewed millions of times online.

The footage showed Garner, 43, and Pantaleo lurching against a glass storefront window and then falling to the pavement. Quickly, Garner, who weighed about 400 pounds (180 kilograms), appeared distressed gasping, “I can’t breathe,” at least 11 times before he fell unconscious.