Eric Garner, 43, died July 17 after being confronted by police on Staten Island for allegedly selling cigarettes illegally.
During the encounter, Garner raised both hands in the air and told the officers not to touch him. Seconds later, a video shows an officer behind him grab the 350-pound man in a choke hold and pull him to the sidewalk, rolling him onto his stomach.
"I can't breathe! I can't breathe!" Garner said repeatedly, his cries muffled into the pavement.
The cause of Garner's death was "compression of neck (choke hold), compression of chest and prone positioning during physical restraint by police," said Julie Bolcer, a spokeswoman for the medical examiner's office. The death was ruled a homicide.
Acute and chronic bronchial asthma, obesity and hypertensive cardiovascular disease were listed as contributing conditions in a controversial death that sparked anti-police demonstrations and calls for a federal investigation.
Douglas Auer, a spokesman for the Richmond County district attorney's office, said the investigation into the death was continuing.
"We await the issuance of the official death certificate and the autopsy report," he said in a statement.
There was no immediate reaction from Garner's family but they were expected to speak at a Harlem rally with the the Rev. Al Sharpton on Saturday.
Mayor Bill de Blasio Friday expressed his "deepest sympathies" to Garner's family.
"My administration will continue to work with all involved authorities, including the Richmond County District Attorney, to ensure a fair and justified outcome," he said in a statement. "We all have a responsibility to work together to heal the wounds from decades of mistrust and create a culture where the police department and the communities they protect respect each other ... I've said that we would make change, and we will. As Mayor, I remain absolutely committed to ensuring that the proper reforms are enacted to ensure that this won't happen again.
The video of the incident showed the Staten Island man lying on the ground motionless after he was taken down by a group of officers. An asthmatic, Garner was later declared dead at a nearby hospital, according to CNN affiliate WCBS. Police said he suffered a heart attack and died on the way to the hospital.
"This is a terrible tragedy that occurred ... A terrible tragedy that no family should have to experience," de Blasio said after the death, calling the video of the incident "very troubling."
Garner, a grandfather with six children, had a lengthy criminal history, including more than 30 arrests, and had been previously arrested for selling untaxed cigarettes in May, according to police.
But demonstrators in New York called the police response during his arrest excessive and criminal.
On July 19, Garner's friends and family rallied with Sharpton in Harlem, demanding a full investigation into Garner's death, according to WCBS.
Officer Daniel Pantaleo, who is seen on the video choking Garner, was put on modified assignment and stripped of his badge and gun as the New York Police Department continues to investigate the incident, WCBS reported. The choke hold tactic is prohibited by the NYPD.
Two EMTs and two paramedics also were suspended without pay, according to Erika Hellstrom, vice president of development at Richmond University Medical Center.
In a statement, Patrolmen's Benevolent Association President Patrick J. Lynch called Pantaleo's reassignment "a completely unwarranted, kneejerk reaction for political reasons." He said the move "effectively pre-judges this case and denies the officer the very benefit of a doubt that has long been part of the social contract that allows police officers to face the risks of this difficult and complex job."
On Friday, the police union expressed "sympathies and prayers" for the Garner family and said it stood "firmly in support of all police officers" put in difficult circumstances.
"Police Officers don't start their days expecting or wanting something like this to occur in the performance of their duties," PBA president Patrick Lynch said in a statement. "The ME's report indicates that Mr. Garner was a man with serious health problems so there will have to be a complete and thorough analysis of all the factors that played a part in this tragedy. We believe, however, that if he had not resisted the lawful order of the police officers placing him under arrest, this tragedy would not have occurred."