NEW YORK (Reuters) - New York City began disciplinary proceedings on Thursday against the police officer who in 2014 applied a fatal chokehold to Eric Garner, an unarmed black man, the Civilian Complaint Review Board said.

FILE PHOTO: People protest against the Staten Island death of Eric Garner during an arrest in July, at midtown Manhattan in New York, U.S., December 3, 2014. REUTERS/Eric Thayer/File Photo

Officer Daniel Pantaleo, who has been on desk duty for the four years since his encounter with Garner on a Staten Island sidewalk, could face termination from the police force following a departmental trial.

His charging comes after the New York Police Department gave the U.S. Department of Justice an ultimatum earlier this week, saying it could no longer wait for a federal civil rights investigation to conclude.

On Thursday the Civilian Complaint Review Board, the city agency known as CCRB that acts as the prosecutor in police administrative trials, said the Justice Department had released its “hold” that put the disciplinary proceedings against Pantaleo on ice.

The police department said in its letter to the Justice Department on Monday that it would begin the disciplinary proceedings on Sept. 1 if federal investigators had not announced whether they would prosecute Pantaleo by then.

Cellphone video footage of Garner repeatedly saying “I can’t breathe!” to Pantaleo, whose arm is around his neck, helped focus national attention on police killings of unarmed black men and fueled the burgeoning Black Lives Matter movement.

Police had approached Garner on July 17, 2014 for peddling loose cigarettes, a violation of the city’s administrative code. The encounter escalated into an argument before Pantaleo began trying to restrain Garner.

The police department has long banned its officers from using chokeholds.

Garner’s family has expressed frustration that no one has been punished for his death, and cautiously welcomed the promise of action against Pantaleo.

“We want them to move forward expeditiously,” Gwen Carr, Eric Garner’s mother, said in a statement. “But we have just been left hanging – and we got the sense that nothing was happening. We want all six police officers involved in my son’s murder to be held accountable.”

The police department said in a statement that the disciplinary proceedings will “commence in the coming days” against both Pantaleo and Kizzy Adonis, a sergeant who was at the scene. The Adonis case does not involve the CCRB.

The CCRB declined to say what internal charges Pantaleo faced. Besides termination, departmental trials can also result in suspension or a docking of vacation days.

Pantaleo’s labor union, the Patrolmen’s Benevolent Association, said it expects Pantaleo to be vindicated.

“We hope that the NYPD’s eagerness to start the disciplinary process does not mean the outcome has already been decided, without even the pretense of due process,” Patrick Lynch, the union’s president, said in a statement.

In 2014, A New York grand jury voted against indicting Pantaleo.

The New York Police Department did not respond to requests for comment.

Devin O’Malley, a Justice Department spokesman, said the police department had been told as early as the spring it could move forward with disciplinary proceedings while the federal investigation continues. City officials, including Mayor Bill de Blasio, disputed this timeline.