Rankin and Willingham are the pair of FBI agents who surreptitiously
search Hannibal Lecter's cell at the Chesapeake State
Hospital once it is discovered that he is in
contact with the "Tooth Fairy" killer. They take Polaroids of the cell
before they search it, to put everything back in the correct place. Following this they search the hospital trash for the envelope that the "Tooth Fairy" killer used to send his message.
When Lloyd Bowman realizes that the messages between the two serial killers are encrypted using a book code, one that must be based on a book in Lecter's cell, he tells Jack Crawford to instruct Rankin and Willingham to meet him at the Library of Congress with the Polaroids of the cell so that together they can determine the book being used.
"HANNIBAL" (Four years before)
It is unknown if Rankin and Willingham will appear before Season 4.