The remains of 24-year-old Valerie Reyes, of New Rochelle, were found last Tuesday in a wooded area on the side of the road in Greenwich.
Police say she was bound at the hands and feet.
The suspect, 24-year-old Javier DeSilva, is expected to be charged with federal crimes and prosecuted by the Southern District of New York. He was arrested in Queens Monday night.
Sources say DeSilva has made admissions in the death, including that it occurred in New Rochelle.
The victim's mother recently said that her daughter was frightened.
"She was just really scared, very frightened," mom Norma Sanchez said. "Fearing for her life."
She says Reyes suffered from anxiety and depression, and that after an ex-boyfriend moved out of her apartment, she became more fearful of dying.
DeSilva is accused of fraudulently using Reyes' ATM card, and police say they believe he was also involved in her death.
The New Rochelle Police Department is expected to release more information.
"We are confident that the pursuit of justice for Valerie will be successful and we continue to work with the family to provide closure to this tragedy," Greenwich police Captain Robert Berry said. "We are asking the public for any information they may possess concerning Valerie and/or her disappearance. Information may be left at the Greenwich Police Tip Line at (203) 622-3333 and email at Tips@greenwichct.org."