Albany The Big Apple’s special narcotics prosecutor is losing a legal eagle to the Cuomo administration.

Gov. Cuomo yesterday tapped Terence J. O’Leary to head the state Health Department’s Bureau of Narcotics Enforcement, where he is ex-pected to expand the bureau’s efforts to fight the theft of prescription drugs, especially those used in mental health, substance abuse and pain management.

O’Leary has been supervising long-term probes of narcotics trafficking.