Alan Stanwyk is one of two of the villains of both the movie and book, Fletch He was played by Tim Matheson.
At the start of the movie, Alan meets with Fletch and asks him to kill him. In return he'll give him $50,000 and a free ticket to Rio de Janeiro. Explaining to Fletch, he's suffering from bone cancer and that by murdering him, would greatly help out his family. Fletch though suspicious of Alan's offer, decides to investigate him and discovers he's not dying of bone cancer, he sold his wife Gail, $3,000 of ranch property in Utah,and has two wives. Fletch also finds out Alan's been flying from Rio and back, smuggling drugs for the second villain, Chief Jerry Karlin. Stanwyk's true plan is to kill Fletch and scam $3 million from his wife in Los Angeles so he can take his Utah wife to Brazil with him and start a new life.
By the end of the movie, this backfires as not only Fletch and Gail catch on, but Chief Karlin too. Thinking that Stanwyk is gonna run with the $80,000, he gave him. He shoots and kills him.