New York — Fentanyl exposure was confirmed as the cause of the day care center death of a 1-year-old Bronx boy, the city Medical Examiner’s office said Friday.

Nicholas Feliz-Dominici’s death was ruled a homicide caused by “acute fentanyl intoxication.”

Law enforcement officers on Thursday arrested Felix Herrera, 34, who had fled the country. He was charged in Manhattan Federal Court with his wife, Grei Mendez, and alleged accomplices Carlisto Acevedo Brito and Renny Parra Parades with conspiracy to distribute narcotics resulting in death.

Prosecutors say they used the day care on Morris Ave. near E. 196th St. in Fordham Manor as a front in their fentanyl trafficking operation.

Grei Mendez and Carlisto Acevedo Brito also face murder charges in Nicholas’ death, and attempted murder charges in the cases of the other children sickened at the day care center. Those charges are being brought in Bronx Supreme Court.

Nicholas had spent just one week at the day care center when he and three other children were rushed to the hospital after coming into contact with the powerful narcotic on Sept. 15.

An initial search of the center uncovered drugs and drug packaging equipment, police said. A later search uncovered a stash of fentanyl hidden under the day care center’s flooring, said cops.