NEW YORK — The New York City medical examiner’s office Friday confirmed what demonstrators had been saying for weeks: A man who died in a confrontation with police was killed by a choke hold an officer applied to his throat.

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.

The choke hold tactic is prohibited by the NYPD and many other departments, but critics say it is still commonly used across the country. Some law enforcement agencies differentiate between holds that are designed to restrict the flow of oxygen (chokes) and those designed to restrict bloodflow to the brain (strangles).

As of 2004, the NYPD’s official policy was as follows:

“Members of the New York City Police Department will NOT use chokeholds. A chokehold shall include, but is not limited to, any pressure to the throat or windpipe, which may prevent or hinder breathing or reduce intake of air.

“Whenever it becomes necessary to take a violent or resisting subject into custody, responding officers should utilize appropriate tactics in a coordinated effort to overcome resistance. … Whenever possible, members should make every effort to avoid tactics, such as sitting or standing on a subject’s chest, which may result in chest compression, thereby reducing the subject’s ability to breathe.”

On Saturday, Garner’s widow, Esaw, appeared at a Harlem rally with the victim’s mother, Gwen Carr, and the Rev. Al Sharpton.

“First of all, I want to thank the God above for giving us justice for my husband so that we can move forward,” she said. “I met with the prosecutors and I feel like I did the right thing by doing that and I just want them to do the right thing and get me justice for my husband.”

Sharpton is planning a march across the Verrazano-Narrows Bridge, which connects Brooklyn and Staten Island, for August 23.

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.

The U.S. Justice Department has said it is monitoring the investigation. If local prosecutors decline to file criminal charges, the federal justice department could conduct an investigation into whether the victim’s civil rights were violated.

“The District Attorney will be examining the case to determine if the use of the choke hold was necessary to subdue and arrest Garner, or was an excessive use of force resulting in death,” legal analyst Paul Callan said.

A former deputy chief of homicide for the Brooklyn District Attorney’s office, Callan said a choke hold does not violate state law but is prohibited by NYPD guidelines on excessive force.

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. 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.

Officer Daniel Pantaleo, who is seen on the video choking Garner, was put on modified assignment and stripped of his badge and gun amid the investigation, the New York Police Department said. A second police officer was placed on desk duty. 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.”

Police Commissioner William Bratton ordered an extensive review of the NYPD’s training procedures after Garner’s death.

After a two-hour meeting with NYPD Training Commissioner Ben Tucker last week, Bratton ordered a “top to bottom review of all the training that this department provides to its personnel, specifically focusing on force, how do we train our officers for a takedown, how do we train them to use the various levels of force that they’re authorized to use.”

“I would anticipate that coming out of this effort that there will be a retraining of every member of the New York City Police Department in the weeks, months and potential years ahead,” Bratton said.