(Reuters) - The New York Police Department on Thursday for the first time made public body-camera video showing a fatal shooting involving some of its officers, a release that the patrolmen’s union criticized as jeopardizing officers’ due process rights.

The NYPD, the largest city police department in the United States, has been slower than some other law enforcement agencies to adopt body cameras and only a fraction of its officers have them.

The footage shows officers opening fire and killing a man who they said was armed with a knife and a fake gun in the Bronx borough on Sept. 6. Police opened fire after pleading with the man, 31-year-old Miguel Richards, to disarm himself during a 12-minute stand-off.

Molly Kovel, a senior staff attorney with the New York Civil Liberties Union, an affiliate of the ACLU, said it was not clear to her Richards had raised his right hand toward the officers before they opened fire, as the NYPD said in a statement.

Regardless, the video reveals that officers need better training in how to reduce tensions when dealing with emotionally disturbed people, she said.

“This video is a really good example of why the public deserves to see body camera videos, because it’s an important window into these encounters and the public needs to decide if training is adequate,” Kovel said.

Police departments around the country have embraced body-cams as a way of protecting officers from unjust accusations, while civil liberty advocates have championed the technology as a way to assure the rights of suspects are protected.

Patrick Lynch, president of the police union the Patrolmen’s Benevolent Association of New York, in a statement said releasing the video “sets a dangerous precedent that jeopardizes police officers’ due process rights and confidentiality protections under state law.”

A representative for the NYPD did not immediately respond to a request for comment on the union’s criticism and the comments by the New York Civil Liberties Union staff attorney.

Police went to the apartment of Richards after his landlord told officers he had not seen the man for some time, the department said in a statement.

Officers found Richards holding a knife in his left hand with his right hand hidden behind his back, clasping what later turned out to be a silver fake gun, the statement said.

Video footage taken from multiple cameras shows officers repeatedly commanding Richards to drop the knife and whatever he was holding in his right hand. Richards was standing behind a bed in his room as officers watched at the doorway.

“I don’t want to shoot you if you have a fake gun in your hand, you hear me? But I will shoot you if that’s a real gun,” one of the officers tells Richards.

Slow-motion footage released by the NYPD appeared to show movement of Richards’ right arm just before the officers fired.

Richards died at the scene and the investigation is open.