The Secret Service combines the two responsibilities into a unique dual objective . The two core missions of protection and investigations synergize with the other , providing crucial benefits to special agents during the course of their careers . Skills developed during the course of investigations which are also used in an agent ’s protective duties include but are not limited to : Protection of the nation 's highest elected leaders and other government officials is one of the primary missions of the Secret Service . After the 1901 assassination of President William McKinley , Congress also directed the Secret Service to protect the president of the United States
assassination of President William McKinley
Assassination of William McKinley
United States Secret Service