NEW YORK (Reuters) - A federal grand jury in New York has begun hearing evidence in the death of Eric Garner, an unarmed black man whose chokehold death at the hands of a white police officer sparked widespread protests, a source familiar with the matter said on Thursday.

A child reads posters at the makeshift memorial where Eric Garner died during an arrest in July, at the Staten Island borough of New York December 3, 2014. REUTERS/Eduardo Munoz

The U.S. Justice Department opened a civil rights investigation of Garner’s death in December 2014, after a grand jury in the borough of Staten Island declined to bring criminal charges against the officer, Daniel Pantaleo.

The decision led to rallies across the city, adding to nationwide tensions over the treatment of minorities by police.

The person familiar with the matter, who spoke on the condition of anonymity to discuss the ongoing investigation, said several police officers have been subpoenaed to testify before the grand jury.

The grand jury proceeding was first reported by The Daily News on Wednesday. A spokeswoman for the U.S. Attorney’s office in Brooklyn declined to comment.

Pantaleo’s lawyer, Stuart London, said he understood a grand jury had been convened but had not yet heard from the Justice Department.

“We’ll let the federal investigation take its course,” he said. He has previously said Pantaleo was doing his job and did not violate Garner’s rights.

Police questioned Garner on a Staten Island sidewalk on July 17, 2014, for allegedly selling loose cigarettes illegally.

The confrontation turned physical and a cellphone video captured the last moments of Garner’s life, when he repeatedly said “I can’t breathe” as Pantaleo held him in a chokehold.

Those words became a rallying cry for protesters across the United States.

Chokeholds have long been banned by New York City Police Department regulations.

The city agreed to pay Garner’s family $5.9 million last July to settle a wrongful death claim.

Jonathan Moore, a lawyer for the family, said he was aware of reports that a grand jury had begun reviewing evidence in the case but could not confirm them.

“The Department of Justice has told us all along that they’re taking the matter very seriously,” he said. “We’re hopeful that they’ll do the right thing.”

The department’s internal probe of Pantaleo’s actions has been on hold as federal prosecutors pursue their investigation.

Last month, the department said Sergeant Kizzy Adonis, who was supervising officers at the scene, was served with disciplinary charges in connection with the incident and placed on modified duty.