Thanks to Molly Kodner for obtaining a copy of this correspondence
McKinley was greeting visitors in the Temple of Music at the Pan-American Exposition on September 6, 1901, in Buffalo, New York, when he was shot twice at close range by lone assassin Leon Czolgosz. As McKinley collapsed, he was caught and supported by his aides, among them Cortelyou. As he was held in their arms he whispered, "My wife... be careful, Cortelyou, how you tell her. Oh, be careful."