From Findagrave:

American Folk Figure. He was an American prodigious savant known as a megasavant. He had a photographic or eidetic memory, but also social developmental disabilities, possibly resulting from congenital brain abnormalities. He was the inspiration for the character of ‘Raymond Babbitt,’ played by Dustin Hoffman, in the 1988 movie “Rain Man.” He was not autistic and likely had FG syndrome.

Located in the Memorial Holladay Cemetery.