I was one of the many bystanders who witnessed part of the major scene which took place on location in front of and inside Sak's 5th Avenue in Manhattan, a lunch hour that turned into two. I believe it was based on a true event and is documented in the NYPD files.As for the movie it was one of the best and well acted movies of the seventies in my opinion. I have been trying to get a copy of it for years.The movies involves a screw-up that leaves a female undercover cop dead because the brass feel asleep and later looked for and found a scapegoat, sound familiar? As I mentioned the acting was great, all of the cast acted as if they been NY City cops at some point in their lives.