Police say 30-year-old Naeem Davis, who is homeless, is charged with second-degree attempted murder and second-degree murder with depraved indifference to human life.
Investigators picked up Davis at 50th Street and Seventh Avenue, just a block from the 49th Street subway station where Ki-Suck Han died Monday.
Davis had been described as mentally ill or emotionally disturbed, but authorities say has no known mental illness history and that he had enough sense to try and change his appearance after the crime took place.
He told detectives the man he pushed onto subway tracks wouldn't leave him alone, an account not disputed by witnesses. The confrontation is believed to have started at the subway turnstile, and detectives are investigating whether Han jumped that turnstile and bumped into Davis.
Davis says Han then followed him onto the platform, where he repeatedly told Han to go away. Instead, he says Han continued to harass him. At some point during the verbal dispute, Davis allegedly shoved the victim in a manner that caused him to go flying onto the subway tracks.
The train is not believed to have been anywhere near the station at the time of the shoving. Davis admitted he stayed on the platform and saw Han get struck by the train.
Officials are awaiting toxicology reports on the victim, who had an empty pint bottle of vodka on him at the time of his death.
Police used surveillance video from commercial establishments to spot Davis, who reportedly was known to work with street vendors near the scene. One of them, newsstand vendor Liz Willis, said she recognized Davis but did not inform police because she didn't want to be a snitch.
"He was different from what he was yesterday," she said. "He shaved his head, beard and everything. He looked different. And I go, 'Oh, that's you.' He goes, 'No, that's not me. The guy is 20 years old.' I said, 'No, but that's you though.' And he's like, 'No, it's not,' and then he walked away."
The funeral for Han, who leaves behind a wife and daughter, is expected to be held in Queens on Wednesday. His wife says the couple had a fight about 90 minutes before the incident.
Davis reportedly has eight prior arrests, including several in Pennsylvania.