FILE - In this April 2, 1968 file photo U.S. Sen. Robert F. Kennedy, D-NY, shakes hands with people in a crowd while campaigning for the Democratic party's presidential nomination on a street corner, in Philadelphia. Friends and family of U.S. Sen. Robert F. Kennedy will host a memorial service at Arlington National Cemetery on June 6, 2018, to honor him on the 50th anniversary of his assassination. (AP Photo/Warren Winterbottom, File)

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