Officer Pedro Serrano, 43 years old, said after he contacted the NYPD's Internal Affairs Bureau to complain, stickers of "rodents" appeared on his locker.

WSJ: A Second NYPD Officer Cites Quotas for Street Stops

"As it would with any such allegation, regardless of its credibility, IAB is investigating it, " said the NYPD's chief spokesman, Paul Browne, referring to the internal affairs bureau.

NPR: NYPD Investigating Actress Bynes Allegations

Bloomberg's office referred calls Tuesday to the NYPD, which said it already gets plenty of oversight from its 700-person Internal Affairs Bureau, a civilian complaint board, a police corruption commission, prosecutors, judges and a 1985 federal court settlement that set guidelines for its intelligence-gathering.

NPR: Lawmakers Reach Deal For NYPD Inspector General