Aaron Katz, who for more than 50 years relentlessly and publicly sought the exoneration of Julius and Ethel Rosenberg, the central figures in the nation’s most controversial spying case, died on Sept. 28 in Venice, Fla. He was 92 and lived in North Port, Fla. The death was confirmed by his wife, Cynthia. Mr. Katz was director of the National Committee to Reopen the Rosenberg Case for 42 years, repeatedly leading demonstrations outside the federal courthouse on Foley Square in Manhattan on the anniversary of the couple’s execution in Sing Sing’s electric chair on June 19, 1953. They had been...