"We can confirm that Daniel Penny will be arrested on a charge of manslaughter in the second degree," the spokesperson for Manhattan District Attorney Alvin Bragg told AFP.

He added that Penny will likely appear in a state court to answer the charge on Friday.

The death of Jordan Neely -- widely identified as a Michael Jackson impersonator who often performed on the train -- earlier this month sparked outrage.

It was caught on camera and angered activists and left-leaning lawmakers, leading to protests calling for the arrest of the alleged perpetrator.

The video showed Neely, 30, on the ground of a subway train as another man, reportedly 24-year-old US Marine Penny, held him around the neck.

Witnesses said the serviceman allegedly restrained Neely after the latter was acting erratically on the train and screaming at passengers for food and drink.

The incident touches on two burning issues in America's financial capital -- the many homeless people suffering mental illness and residents' fears for their safety on the underground.

It also had a racial element -- Neely was Black and Penny is white.

Family and friends told local media that Neely had a history of mental illness, like many living on the streets in the country's biggest city, with almost nine million residents.

Reports said Neely had been arrested dozens of times and that his mother had been murdered when he was a teenager.

Mental health and homeless activists said the city had failed Neely. Left-wing congresswoman Alexandria Ocasio-Cortez of New York said Neely had been "murdered."

Protesters -- including some who spilled onto subway tracks last weekend, sparking several arrests -- decried Neely's death as an example of white "vigilanteism."

Some social media users praised Penny for intervening but many criticized the level of force used.

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