I'm have to assume that these 500 cops were on the street because of Bill Clinton's federal dollars.
IIRC, the Clinton funding of 100,000 new cops on the street had a built-in sunset where the federal funding was heavy on the front end and then it backed off over a period of, I don't know, three or four years, leaving the state or city to make up the difference.
So NO might have legitimately hired cops but when the funding ran out, they probably just kept them on "in name only" and used what funds were available for other things.