Assistant Director Walter Sergei Skinner is one of the heads of the FBI. An ex-Marine with a stern sense of duty, Skinner has little patience with Agent Mulder´s unorthodox methods of investigation, and he has warned Scully and Mulder that their inquires have been crossing into dangerous territory more than once. He once even shut down the X-Files entirely, but he reopened them when Agent Scully was kinapped, telling Mulder "that´s what they fear the most" without clearifying who "they" are. Eventhough it´s never clear whose side he is on, or whose orders he takes, but his efforts on behalf of Mulder and Scully "through unofficial channels", have made it plain that he is deeply concerned about his agents and their work.