Renato Seabra, 21, remained silent at his arraignment in Manhattan State Supreme Court. His lawyer entered a not-guilty plea on his behalf.
Authorities say Castro was castrated and killed in a Manhattan hotel room on January 7.
Model Renato Seabra admitted castrating 65-year-old Carlos Castro at the InterContinental New York Times Square hotel, according to a court document.
A male model who had recently been a contestant on a Portuguese reality TV show was taken into police custody hours after his companion, a celebrity Portuguese television journalist, was found castrated and bludgeoned to death in a New York City hotel.
Police are still on the scene investigating the gruesome murder of a Portuguese journalist at the Inter-Continental New York Times Square Hotel.