Bet nobody sent Whoopi and Ted Danson or Whoopi and Frank Langella death threats when they were together. Sounds like a disenchanted male or female fan who fantasized about one or the other of these actors.
Sounds about right. Maybe some stalker, male or female.
If the other letters are from Ohio and Penn. that's no biggie...someone coming to NYC from Ohio could mail letters in all 3 places on the same day. (There are also other ways of the same person could have done it).