Advance preparations for President Kennedy’s visit to Dallas were primarily the responsibility of two Secret Service agents: Special Agent Winston G. Lawson, a member of the White House detail who acted as the advance agent, and Forrest V. Sorrels, special agent in charge of the Dallas office.[C2-17] Both agents were advised of the trip on November 4.[C2-18] Lawson received a tentative schedule of the Texas trip on November 8 from Roy H. Kellerman, assistant special agent in charge of the White House detail, who was the Secret Service official responsible for the entire Texas journey.[C2-19] As advance agent working closely with Sorrels, Lawson had responsibility for arranging the timetable for the President’s visit to Dallas and coordinating local activities with the White House staff, the organizations directly concerned with the visit, and local law enforcement officials.[C2-20] Lawson’s most important responsibilities were to take preventive action against anyone in Dallas considered a threat to the President, to select the luncheon site and motorcade route, and to plan security measures for the luncheon and the motorcade. Preventive Intelligence Activities The Protective Research Section (PRS) of the Secret Service maintains records of people who have threatened the President or so conducted themselves as to be deemed a potential danger to him. On November 8, 1963, after undertaking the responsibility for advance preparations for the visit to Dallas, Agent Lawson went to the PRS offices in Washington. A check of the geographic indexes there revealed no listing for any individual deemed to be a potential danger to the President in the territory of the Secret Service regional office which includes Dallas and Fort Worth.[C2-21] To supplement the PRS files, the Secret Service depends largely on local police departments and local offices of other Federal agencies which advise it of potential threats immediately before the visit of the President to their community. Upon his arrival in Dallas on November 12 Lawson conferred with the local police and the local office of the Federal Bureau of Investigation about potential dangers to the President. Although there was no mention in PRS files of the demonstration in Dallas against Ambassador Adlai Stevenson on October 24, 1963, Lawson inquired about the incident and obtained through the local police photographs of some of the persons involved.[C2-22] On November 22 a Secret Service agent stood at the entrance to the Trade Mart, where the President was scheduled to speak, with copies of these photographs. Dallas detectives in the lobby of the Trade Mart and in the luncheon area also had copies of these photographs. A number of people who resembled some of those in the photographs were placed under surveillance at the Trade Mart.[C2-23]