The material Joe Paterno and his staff turned over to the FBI during his Penn State tenure included the wrapping from a mysterious fruitcake.
Two Penn State players, according to an FBI memo, ate the cake, believing it had come from one of their high school coaches. After speaking to the coach, they realized it had not, and reported the incident to Paterno. According to files (which did not contain any material on the Jerry Sandusky case), it seems the mystery of the fruitcake was never solved. (The players were OK.)
Among the rest of the material are some disturbing death threats, like this one.
Another letter is from a University of Pittsburgh fan complaining that a Penn State player was too scared to play at Pittsburgh. "Why didn't [name redacted] go to Pitt? a) Pitt academic standards were to high! (sic) b) Pitts 4 yr. football schedule was too tough."
One letter threatened an assistant.
Here's another matter-of-fact murder threat. (These letters are from the time before the Sandusky case was made public; the only thing that seems to have inspired the threats was simply the fact that Paterno was a public figure.)
A large part of the file is dedicated to a writer who ends his letters with "A Bitter Father," who also threatens Paterno's life. He claimed to be the father of a player Paterno coached. "Let me try to explaine what happened in the first place if I can," the "Bitter Father" wrote in one letter. "Quite a few years ago my son had a scholarship to Penn State. His mother and me builtdt our whole life around him. Things did not work out like we had planned. He spent two years there then left school."
A few lines later, he added "He just went to the dogs -- drinking & drugs. I always blamed Penn State for this." In that same letter, he apologized, saying he had spoken to a priest and learned not to blame his problems on others.
But like many of the other writers in the file, he was not identified, and it is not clear if the FBI ever caught him.