On the night she was attacked, Ms. Gustern had left her apartment to watch one of her students perform at Joe’s Pub at the Public Theater on Lafayette Street.
She was able to give a description of her assailant to the police shortly after the incident.
Ms. Pazienza’s arrest followed a dayslong search by the New York City police, who posted photos and video of the attacker.
On March 16, the day after Ms. Gustern died, Ms. Pazienza left New York City for her parents’ house in Long Island, the court documents said. Following a tip received from an anonymous source, the police went there on Monday morning, but her father would not allow officers to enter and claimed she was not there, the documents said.
Ms. Pazienza’s lawyer, Arthur Aidala, then contacted police and arranged for her to surrender on Tuesday morning, the documents said.
After the hearing, Mr. Aidala said his client was distraught.
“She was crying. She was in pain. She’s accused of a very horrible act,” he said. “She’s a very moral, right, just person. She was treated by the D.A.’s office in a very inconsistent manner. She has no criminal record.”
Relatives of Ms. Pazienza could not immediately be reached for comment.
Former students of Ms. Gustern remembered her as fierce, supportive and loving. She taught out of her apartment, with a grand piano in her living room and an electronic piano in her bedroom, where her students practiced vocal exercises so as not to disturb her neighbors.
Melinda Pope DeRocker first turned to Ms. Gustern in 1997, when she was looking to get back into singing after becoming a music director. Ms. Gustern taught her how to open up her vocal range, she said. When Ms. DeRocker had her thyroid removed 11 years ago, it was Ms. Gustern who gave her the confidence to sing again without fear.