Thomas "Lem" Johns, a former secret service agent present during the assassination of President John F. Kennedy and swearing in of Lyndon Johnson, has died. He was 88.

Grandson Mike Johns said the former secret service agent died Saturday in Alabama.

Judge Sarah T. Hughes administers the Presidential Oath of Office to Lyndon Baines Johnson aboard Air Force One, Nov. 22, 1963. (Cecil Stoughton, White House/John Fitzgerald Kennedy Library, Boston)

Lem Johns is pictured in iconic photos from Nov. 22, 1963 aboard the presidential plane where Johnson was sworn in. One photo shows Johns standing behind former first lady Jacqueline Kennedy as Johnson consoles her following the oath of office.

Johns was assigned to Johnson's security detail at the time of the shooting and was riding in the motorcade when the shots were fired.

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