Using a composite sketch, the girl's brother launched an all-out search for the attacker not far from the scene of the crime.
"He has his mother join him and they talked to neighbors who were able to identify an apartment of the suspect," said Montclair Police Detective Debbie Canou. "That information was provided to the Montclair Police Department. A follow-up investigation confirmed his involvement and he was arrested."
The suspect was found Saturday night and booked at West Valley Juvenile Detention Center.
The suspect's name was not released because he is a 13-year-old minor.