The attacks are believed to have begun in January, and most occurred on the Upper East Side in the lobbies or entryways of the victims' homes.
He would come up behind women and grab them in the groin, breasts or rear end. He often reached up their skirts.
In recent days, the suspect has moved away from buildings, striking on a No. 6 train at 68th Street and Lexington Avenue last week, and inside Central Park on Friday.
The police tip came from a man who works in the Upper East Side building that houses the restaurant where Hernandez was employed.
Women on the Upper East Side said they had been concerned about the groper reports.
"I feel better already," said Hilary Beckman.