No one can really comment on this without knowing the details and given the drunken nature of the whole affair that'll probably never be fully disclosed.
What worries me most is that allegedly, the cop was carrying a knife. NYPD are not without controversy though.
"Amadou Bailo Diallo (September 2, 1975 – February 4, 1999) was a 23-year-old immigrant from Guinea who was shot and killed in New York City on February 4, 1999 by four New York City Police Department plain-clothed officers: Sean Carroll, Richard Murphy, Edward McMellon and Kenneth Boss, who fired a combined total of 41 shots, 19 of which struck Diallo, outside his apartment at 1157 Wheeler Avenue in the Soundview section of The Bronx. The four were part of the now-defunct Street Crimes Unit. All four officers were acquitted at trial in Albany, New York.[1]Diallo was unarmed at the time of the shooting, and a firestorm of controversy erupted subsequent to the event as the circumstances of the shooting prompted outrage both within and outside New York City. Issues such as police brutality, racial profiling, and contagious shooting were central to the ensuing controversy."