Margaret Truman has died. Mrs. Daniel was multifaceted - a presidents daughter who was also a singer, actress,and (most recently) a prolific mystery writer.
She was twice Mystery Guest - first on January 25, 1953, and served as a panelist four or five times in the mid-1950's. She was a guest panelist on March 21st 1954 and was (from fallible memory) the earliest guest panelist still living. Phyllis Cerf, until her death last year, held that distinction. I think Betty White (guest panelist June 19th 1956) now has that record.