New York, New York - Daniel Penny pleaded not guilty Wednesday over the chokehold death of Jordan Neely on the New York subway, prosecutors said.

The former US Marine was arraigned in Manhattan and pleaded not guilty to second-degree manslaughter and criminally negligent homicide in the death last month of Neely, a spokesman from the Manhattan District Attorney's Office told AFP.

The manslaughter charge accuses Penny of "recklessly" causing the death of 30-year-old, who was a homeless Black man, but stops short of saying he had intent to kill.

If convicted, Penny could spend up to 15 years in prison.

Murder Luigi Mangione: Resume and social media posts of suspect in killing of UHC chief exec unearthed

Neely's death on May 1 sparked outrage after it was caught on camera, as video shared widely on social media showed Neely on the ground of a subway train and Penny holding him around the neck for several minutes in front of onlookers.

Penny "continued his chokehold for several minutes, including after Mr. Neely's body stopped moving," a statement from the Manhattan District Attorney's Office said.

Witnesses said the serviceman restrained Neely after the latter was screaming at passengers for food and drink and said he was willing to die.

Neely was reportedly not physically threatening anyone.

Family and friends told local media that Neely had a history of mental illness, like many living on the streets of New York.

Protests erupted in New York after Neely's death, resulting in several arrests, as some called Penny's actions "white vigilantism."

The city's medical examiner said that Neely was killed by "compression" of the neck, and ruled the death a homicide.

A crowdfunding effort in support of Penny – who has attracted support from many high-profile Republicans – has raised more than $2.9 million on GiveSendGo, a platform known for facilitating funding of far-right figures.