Jerome Sax was a contract killer responsible for the death of NCIS Special Agent Jack Patterson. He also infiltrated the NCIS building pretending to be an old co-worker of Patterson in order to get information on the case they were working on. When Gibbs and Tony traveled to the desert to rescue the artist, Dina Risi that gave Patterson the evidence, Sax arrived with another man on an helicopter and attempted to kill the group with a machine gun.