Richard Lavoie, chief of security for International Telegraph and Telephone, died of a heart attack on December 27, 1972. At the time Lavoie was guarding Ditta Beard, an ITT secretary who claimed she had a memo that her company had contributed $400,000 to Nixon’s campaign fund so that John Mitchell would not bust up some of ITT’s holdings. When columnist Jack Anderson broke this story, Miss Beard was moved from Washington to Denver, Colo., where she was hospitalized for an apparent heart attack. She was whisked away, Anderson claimed, so that she couldn’t testify. Miss Brussell suspects that Lovoie may have heard too much from Dita Beard.