Handwritten letter from George de Mohrenschildt?
The Warren Commission concluded that Lee Harvey Oswald acted alone in the assassination of President John f. Kennedy, that he was not tied to any intelligence agency, and that none of his associates were tied to the assassination. Nevertheless, speculation continued to center about one of Oswald's associations: George de Mohrenschildt and de Mohrenschildt's background. The Warren Commission concluded about de Mohrenschildt: The Commission's investigation has developed no signs of subversive or disloyal conduct on the part of either of the de Mohrenschildts. Neither the FBI, CIA, nor any other witness contacted by the Commission has provided any information linking the de Mohrenschildts to subversive or extremist organizations. Nor has there been any evidence linking them in any way with the assassination of President Kennedy.(1)
http://mcadams.posc.mu.edu/russ/jfkinfo4/jfk12/hscademo.htm