Sklar worked on the Garrison side of the story while Stone added the Oswald story, the events at Dealey Plaza and the "Mr. X" character. Sklar spent a year researching and writing a 550-page triple-spaced screenplay and then Stone rewrote it and condensed it closer to normal screenplay length. Stone and Sklar used composite characters, most notably the "Mr. X" character played by Donald Sutherland. This was a technique that would be criticized in the press. He was a mix of Richard Case Nagell and retired Air Force colonel Fletcher Prouty, another adviser for the film and who was a military liaison between the CIA and the Pentagon. Meeting Prouty was, for Stone, "one of the most extraordinary afternoons I've ever spent. Pretty much like in the movie, he just started to talk." According to Stone,