A surveillance image shows the suspect who police say approached the girl in the elevator of a building near Malcolm X Boulevard and 145th Street around 5 p.m. on June 6.
Investigators say the man grabbed the child's rear end and then ran away.
The suspect is described as a black male, between 25 and 30 years old, approximately 5-foot-6 with a medium build. He was last seen wearing blue jeans and long-sleeved, buttoned shirt.
Anyone with information is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS.
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