Investigators released a picture of the suspect.
They say he's grabbed at least two 12-year-old girls from behind on numerous occasions on the B1 bus near 86th Street and 20th Avenue.
The incidents happened last September through November.
The individual is described as a light skinned man, 5'8", with salt and pepper hair and a mustache; last seen wearing a black jacket.
Anyone with information in regards to this incident is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).
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