The proceedings before a federal grand jury in Brooklyn looking into the death of Eric Garner
at the hands of police Officer Daniel Pantaleo began Wednesday with the testimony of two police officers, according to the official.
Garner's death in July 2014 -- which was ruled a homicide -- led to anti-police demonstrations throughout the nation after a Staten Island grand jury declined to charge Pantaleo.
Top Justice Department lawyers had weighed whether to move forward with the case for months, according to officials familiar with the investigation. The decision to present evidence to a federal grand jury signals they will seek charges in the case, the officials said.
Pantaleo's attorney, Stuart London, denied that "a federally protected right was violated" during the police encounter. He said his client did not use a chokehold but a "take-down method" learned in the police academy.
"This was a police officer just doing his job," London said Thursday. "It was a simple street encounter with no animosity toward Mr. Garner."
London said no decision has been made about Pantaleo, who has not been called to testify, appearing before the grand jury.
Former U.S. Attorney General Eric Holder announced in December 2014 that federal officials were moving ahead with their investigation.
The investigation, which began in earnest after the grand jury declined to indict the officer,
has been examining everything from the actions of the responding officers and paramedics on the Staten Island street where Garner died to the role NYPD training may have played in the death, a senior law enforcement told CNN last year.
The New York City Police Department prohibits chokeholds.
During Garner's fatal police encounter on July 17, 2014, he raised both hands in the air and told the officers not to touch him. Seconds later, a video shows an officer behind Garner grab him and pull him to the sidewalk, rolling him onto his stomach.
"I can't breathe! I can't breathe!" Garner is heard saying repeatedly, his cries muffled into the pavement.
Garner, 43, was pronounced dead that day. Police had suspected Garner of selling cigarettes illegally.
The cause of Garner's death was "compression of neck (chokehold), compression of chest and prone positioning during physical restraint by police," the medical examiner's office has said. It was ruled a homicide.
The medical examiner also listed acute and chronic bronchial asthma, obesity and hypertensive cardiovascular disease as contributing factors in Garner's death.
After reaching a $5.9 million pretrial settlement last year
in a civil lawsuit against the city, Garner's mother, Gwen Carr, renewed calls for federal charges.
The garner case became emblematic of longstanding tensions between police and minority communities, especially given that many of the people stopped under the NYPD's former "stop-and-frisk" police policy have been African-American or Hispanic.
A federal court ruled that stop-and-frisk was unconstitutional and tantamount to racial profiling.
Garner's death came weeks before the racially charged police shooting of unarmed teen Michael Brown in Ferguson, Missouri.
Separate grand jury decisions declining to prosecute police officers in connection with both deaths sparked national protests that sometimes involved clashes with police.
Pantaleo was put on modified assignment and stripped of his badge and gun amid the investigation, and the NYPD commissioner ordered an extensive review of training procedures.
The incident -- and perhaps the subsequent protests -- triggered reforms in how police go about their business, particularly in minority communities.
Justice Department officials declined comment, as is standard on grand jury matters.