Vincent Mroz Vincent Peter Mroz ( March 11 , 1922 – July 22 , 2008 ) was a United States Marine Corps veteran , having served during World War II , and a United States Secret Service agent . In 1948 , he was assigned to the presidential protection detail during the Harry S . Truman and Dwight D . Eisenhower administrations . He served with the Secret Service for 26 years , retiring in 1974 as the Deputy Assistant Director of the uniformed division . In November 1950 , Mroz gained national attention for his involvement in the " biggest gunfight in Secret Service history " during an assassination attempt on President Truman by two Puerto Rican nationalists . Mroz was credited with shooting one of the assailants in the chest and disarmed the body of a second assailant . Mroz had earlier played college football for the University of Michigan and Michigan State College . Early years . Vincent Mroz was born in Stanley , Wisconsin in 1922 , the son of Polish immigrants . His family later moved to East Chicago , Indiana . Mroz attended Washington High School as part of the Class of 1941 . In the fall of 1940 , he played at the guard and tackle positions for the Washington High School football team . At the time of the 1940 United States Census , he was living in East Chicago with his mother Antonia and his stepfather Martin Gzik . Marriage and family . While still serving in the military , Mroz ( then a lieutenant in the Marine Corps ) was married in October 1945 to Shirley Gamm at the Mt . Vernon Place Methodist Church in Washington , D . C . They had two children , Barbara and Gregory Mroz . Secret Service . In 1948 , Mroz went to work for the United States Secret Service . He was assigned to the presidential protection detail . 1950 attack on Blair House . On November 1 , 1950 , Mroz engaged in a gunfight with two Puerto Rican nationalists who stormed the Blair House in an assassination attempt on President Harry S . Truman . The president was temporarily living at Blair House while the White House was undergoing renovations . While President Truman napped on the second floor , one of the attackers , Oscar Collazo , shot a White House police officer at the guard house and began walking up the front steps of Blair House . After hearing the gunshots , Mroz ran through a basement corridor and stepped out of a street - level door on the east side of the House , where he opened fire on Collazo . Mroz stopped Collazo on the outside steps with a bullet to the chest . The incident has been described as " the biggest gunfight in Secret Service History . " Two other officers took part in the shooting of the attackers . After the shooting ceased , Mroz discovered the body of the second attacker , Griselio Torresola , in the hedges adjacent to Blair House . He had been shot by another officer , Floyd Boring . Mroz removed a gun from Torresola ' s body and found two magazines of ammunition in his pockets . In December 1951 , President Truman , described as being " deeply moved , " decorated Mroz and Floyd Boring , described as " two straight - shooting secret service agents , " with silver lapel buttons for their roles in preventing his assassination . Collazo survived and was put on trial in February 1951 . At the trial , Mroz identified Collazo , " He ' s sitting right there with a brown suit and a red tie and glasses on . " Later years . Mroz continued to work in the presidential protection detail during the Truman and Eisenhower administrations . From 1960 to 1962 , Mroz was the chief of the Charleston , West Virginia office of the Secret Service , where he gained note for his investigation of a counterfeiting ring . From 1963 to 1965 , he was the head of the Kansas City office of the Secret Service . He worked for the Secret Service for 26 years . By 1971 , Mroz held the position of Deputy Assistant Director , Protective Services . He retired in 1974 as the Deputy Assistant Director of the Uniformed Division . Later years . Mroz was retired for 34 years . He died at his home in Adrian , Michigan , in July 2008 .