US Attorney General Eric Holder makes a statement about the grand jury decision not to seek an indictment in the Staten Island death of Eric Garner during an arrest in July, in Washington December 3, 2014. [Photo/Agencies]

NEW YORK - US Attorney General Eric Holder on Thursday promised a full investigation into the choking death of an unarmed black man by a white New York police officer as protests flared for a second day over a grand jury's decision declining to bring criminal charges in the case.

Reaction to Wednesday's decision not to indict officer Daniel Pantaleo for his role in the videotaped confrontation that left 43-year-old Eric Garner dead echoed a wave of outrage sparked nine days earlier by a similar outcome in the fatal shooting of an unarmed black teenager by a white policeman in Missouri.

Pantaleo could still face disciplinary action from an internal police investigation, his lawyer said, adding that he expects that process to move quickly and that his client would be exonerated.

A departmental investigation will likely focus on whether Pantaleo employed a chokehold, banned by New York Police Department regulations, in restraining Garner as he and other officers sought to arrest him for illegally selling cigarettes on a sidewalk in July.

In addition to triggering protests around the country, the New York and Missouri cases have re-ignited debate over a US law enforcement system widely perceived to unfairly target and African Americans and other minorities.

Speaking in Ohio, where he announced US Justice Department findings of systematic excessive force by Cleveland's police, Holder said officials must do more to repair the trust between police officers and the communities they patrol.

The Cleveland investigation, which began in March 2013, gained prominence after a police officer there last month shot dead a 12-year-old boy who was carrying what turned out to be a pellet gun on a playground.

New York City Mayor Bill de Blasio, who took office in January promising to improve relations between minorities and police, told reporters on Thursday the city's thousands of patrol officers would undergo extensive retraining.

"The relationship between police and community has to change," he told a news conference. "People need to know that black lives and brown lives matter as much as white lives."

CHOKEHOLDS BANNED

Pantaleo's lawyer, Stuart London, said in an interview Thursday that his client testified to the New York grand jury that he never put pressure on Garner's neck. Instead, Pantaleo said he used a proper takedown technique, London said.

Patrick Lynch, president of the patrolmen's union, agreed, calling Pantaleo a "model" officer at a news conference.

The city's medical examiner has said police officers killed Garner by compressing his neck and chest, adding that Garner's asthma and obesity had contributed to his death.

Video footage from a bystander's mobile phone of Garner being subdued by four police officers just before he died shows Pantaleo's arm pressed across Garner's throat as he lay on a Staten Island sidewalk, repeatedly gasping, "I can't breathe" -- a phrase that has become a rallying cry by demonstrators.