Authorities arrested Erika Menendez Saturday after someone recognized her from surveillance video. Footage showed Menendez shoving a man from India in front of a speeding train's path on Thursday.
Prosecutors say Menendez told authorities she has hated Hindus and Muslims since the Sept. 11 terrorist attacks.
"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," Menendez told police, according to the Queens district attorney's office.
Menendez also told authorities she spontaneously pushed Sunando Sen, 26, because she "thought it would be cool".
Authorities say the suspect laughed so hard throughout her arraignment in Queens criminal court that Judge Gia Morris told her lawyer: "You're going to have to have your client stop laughing."
Her Defense attorney Dietrich Epperson said Menendez's behavior in court was no different from how she had been acting when he spoke to her privately, and said his client didn't really think the proceedings were funny.
Menendez was mumbling and cursing to herself before she knocked Sen on the tracks, according to witnesses.
Menendez has been charged with murder as a hate crime. She is being held without bail. Her next court appearance is scheduled for Jan. 14.
The Associated Press contributed to this report.