14-year-old Cesilia attended St. Alphonsus Commercial High School in the New York borrough of lower Manhattan in 1976. Her family lived in the borough of the Bronx. Cesilia used the subway to get to and from school. Cesilia took the Number Two Train at the 149th Street Station in Manhattan. She would travel 5 stops down the line to her exit at the Simpson Street Station in the Bronx. Cesilia took the Number 5 bus from that subway to her family's home every school day.
On October 6, 1976, Cesilia was last seen by her friends at the 149th Street Station between 3:00 and 4:00pm. She never made it home and hasn't been seen since. Several days after Cesilia disappeared, a witness came forward and told her family that she had seen Cesilia after the reported last sighting of her. The witness stated that Cesilia was on the corner of 163rd Street and Southern Boulevard with a man named Anthony "Rudy" Flores. He was holding Cesilia by her arm and she appeared frightened of him. Rudy claims that he was never with Cesilia on the day of her disappearance and he's got nothing to do with her case. He is also a suspect in the disappearance of 9-year-old Nelida De Jesus De Valle from Boston during that same year, but he's not charged in her case either.
Rudy is currently incarcerated and Cesilia's case remains unsolved. Cesilia is a Hispanic female with black hair & brown eyes. She has a scar on her left forearm. Cesilia was last seen wearing a parochial school uniform which consists of a light gray jacket, a gray plaid skirt, and white blouse.