attorney for the New York City borough of Queens said Erika Menendez, 31, who was seen pacing the subway platform and muttering to herself before the attack, had told investigators that she pushed the victim, Sunando Sen, 46, on Thursday because "I hate Hindus and Muslims."
Menendez was taken into custody in Brooklyn by authorities acting on a tip from someone who recognized the suspect from video of the incident that was aired on television, a spokeswoman for the district attorney told Reuters.
"The defendant is accused of committing what is every subway commuter's worst nightmare - being suddenly and senselessly pushed into the path of an oncoming train," district attorney Richard Brown said in a statement.
"Beyond that, the hateful remarks allegedly made by the defendant and which precipitated the defendant's actions can never be tolerated in a civilized society," he said.
The prosecutor's statement quoted Menendez as telling investigators: "I pushed a Muslim off the train tracks because I hate Hindus and Muslims ever since 2001 when they put down the twin towers I've been beating them up."
Her alleged admission was an apparent reference to the Sept 11, 2001, attack on Manhattan's World Trade Center by Muslim extremists who flew two hijacked jetliners into the twin towers.
Brown's statement gave no indication of the victim's ethnicity or religion or Menendez might have taken Sen to be a Muslim.
The spokeswoman for the prosecutor's office, Meris Campbell, said she did not believe the victim was wearing any clothing that would have led someone to identify him as being a Muslim.
Menendez is awaiting arraignment in Queens Criminal Court on a criminal complaint charging her with second-degree murder as a hate crime, an offense that carries a minimum sentence of 20 years to life in prison.
The minimum penalty for second-degree murder alone is 15 years to life, Campbell said.
If convicted, Menendez could face a maximum penalty of 25 years to life.
Witnesses told police a woman appeared to be mumbling and pacing Thursday evening before she approached an unsuspecting man from behind on the platform of an elevated station in the borough of Queens.
She then shoved him onto the subway track as the train pulled into the station, witnesses said. Brown said Sen died of multiple blunt-force trauma.
After shoving Sen on Thursday, the suspect ran from the station to the street in a scene caught on surveillance video footage that police released on Friday as they searched for her.
Sen's death was the second this month of a New York subway rider pushed onto the tracks of the city's more than 100-year-old subway system.
On Dec 3, Ki-Suck Han was killed after being shoved onto subway tracks in Manhattan as a train entered a station near Times Square.
A suspect, Naeem Davis, has been charged with second-degree murder. Authorities have disclosed a possible motive.
Including Thursday's incident, 139 people have been struck by New York City subway trains so far in 2012, and 54 of them died, a Metropolitan Transportation Authority spokesman said on Friday.
He said the tally was preliminary and subject to change.