You're about 44 years late on this one! I'm excited for you if this is your first time watching it. Imagine 1980 and this film in that era! I highly recommend watching Friedkin interviews. The screenplay is actually based on an actor, Paul Bateson, who appeared in Friedkin's The Exorcist. In the scene where Reagan is at the hospital getting her brain scanned, the medical technician was actually the murderer Cruising was based on. Friedkin would often use real people in his films as he got his start as a documentarian. Bateson was throwing the bodies in the Hudson River in bags that had New York Hospital on the label and the police were able to track the bags back to Bateson. After he was convicted, Friedkin would visit him in prison and it gave him the idea for the film. Look it up! Friedkin often said that life is about the mystery of fate or faith. That said, he didn't like clean endings to any of his films. Murders often go unsolved. I could listen to Friedkin talk forever; he was a very fascinating and interesting person. RIP