Of three ricin-laced letters mailed this month to public officials, only one made it into the hands of an intended target, 80-year-old Mississippi judge Sadie Holland. Investigators are working to piece together what motivated someone to send the letters to her, President Barack Obama and U.S. Sen. Roger Wicker. Holland is a common link between two men who have been investigated in the case. Holland presided over a 2004 assault case against Paul Kevin Curtis, an entertainer who had been the top suspect in the case until prosecutors dropped charges against him Tuesday.