Police are investigating a deadly confrontation in the New York City subway system, CBS New York’s Ali Bauman reports.

Sources tell the station a former Marine restrained another passenger who was acting erratically on a train in a station in the SoHo section of Manhattan Monday afternoon.

Bauman obtained video of the incident. It shows a 24-year-old man putting a 30-year-old man in a chokehold. The first man holds the other around the neck for two minutes and 55 seconds of the video.

Two other riders try to restrain the 30-year-old’s arms before all three let him go, motionless on the floor.

Police sources told CBS New York the 30-year-old in the video had been acting erratically on the train, allegedly throwing trash and yelling at passengers.

CBS New York was told the 24-year-old stepped in to try to quell him, and things got physical. Police told CBS News it wasn’t clear who the aggressor was. Sources say the younger man put the other one in a chokehold while telling those around them to call 911. 

Police told CBS News that when officer arrived, the older man, unresponsive, was brought to a hospital, where he was pronounced dead.

Police told CBS News they took the 24-year-old into custody for questioning but released him without charging him and it wasn’t clear whether he would ever be charged.

Detectives are investigating and waiting for the medical examiner to determine the 24-year-old’s cause of death.

Police weren’t releasing the names of either man.

Criminal defense attorney and former prosecutor David Schwartz told CBS New York self-defense may be a tough legal argument in this situation if the 30-year-old is charged. “You can only assert as much force as necessary in that particular situation, so was force even necessary? I don’t know. We have to see what the investigation unfolds. Was there another way to subdue this person besides getting him into a chokehold?”

But, said Schwartz, whatever happened before the video starts could determine which way the case goes.

“Was this person just causing havoc or (was he) threatening the lives of others on the subway?” Schwartz remarked. “I think the city of New York has created conditions as such where things like this are gonna happen.”

Police sources told CBS New York the man who died has more than 40 prior arrests and an active warrant out for his arrest from a felony assault charge.