Jordan Neely, a 30-year-old Black man, died on Monday in a New York City subway after a passenger held him in a chokehold until his body went limp, said police officials.
The city's medical examiner confirmed that Neely died from compression of the neck.
The passenger, a 24-year-old Marine veteran who appeared to be white, was questioned and released without charges. His name has not been publicly released.
Neely was recognizable to some in New York as he regularly impersonated Michael Jackson and danced in the Times Square transit hub.
Eyewitness: Neely did not physically attack anyone
A video of the encounter posted online by Juan Alberto Vazquez, a freelance journalist, showed a man lying beneath Neely asking other passengers to call emergency services and holding Neely in a headlock position while Neely tried to break free.
Another passenger pinned Neely's arms while a third person held down his shoulder. He lost consciousness during the struggle.
It remains unclear why the group was trying to restrain Neely.
Neely was screaming in "an aggressive manner" while complaining of hunger and thirst, Varquez told the New York Post. He added that Neely did not physically attack anyone.
The medical examiner called Neely's death a homicide but noted that the determination of criminal culpability would be left to the legal system.
The Manhattan district attorney's office said it was investigating the case.
Protesters call for criminal charges against Marine veteran
Protesters gathered Wednesday at the subway station where Neely died to call for an arrest.
Last year, after a shooting on a subway left 10 people wounded, Mayor Eric Adams promised to deploy additional police officers and mental health workers throughout the transit system.
Dave Giffen, the executive director at the Coalition for the Homeless, accused the city and state officials of inadequate response to the homelessness and mental health crisis. He questioned why the Marine veteran was not facing criminal charges.
"The fact that someone who took the life of a distressed, mentally ill human being on a subway could be set free without facing any consequences is shocking," he said.
Reverend Al Sharpton, an American civil rights activist, demanded that Neely's death be investigated as manslaughter.
He referenced a 1984 case where a white gunman was convicted of a weapons offense after he shot four Black men on a subway train.
"We cannot end up back to a place where vigilantism is tolerable. It wasn't acceptable then and it cannot be acceptable now," said Sharpton.