It appears that a former deputy in NY had some firearms that had been previously seized by the police in his personal possession even though they were suppose to be destroyed. One of the items in his possession was a silencer. While it appears that active duty police are permitted to have silencers, once they are no longer a police officer they cannot possess them. The specific details on how he received the silencer are not know, but even if he legally possessed it, once he was no longer a police officer his possession in NY would be in violation of the law.
We are often contacted by NY police officers wanting to set up gun trusts to buy silencers in NY and generally advise against it because of the risks of separation from the police and the consequences. Some police officers form trusts and buy and keep NFA firearms in other states where they are legal but it is risky to bring them to NY.