The scene is shot after Dr. Lecter was moved out of his cell to meet with Sen. Martin. Clarice then meets him one last time at the state prison in Tennessee. She wants to know the real name of Buffalo Bill. He said, "Dr. Chilton, I presume" when Clarice wanted the real name for the last time. It is not clear to me the logic behind using Dr. Chilton's name with Buffalo Bill by Dr. Lecter.
Can anyone help me with this part?