Mainstream Earth-616 biography:
William Baker was born in a rough neighborhood in New York. Abandoned by his father when he was three-years old, William stole and cheated his way through adolescence. Expelled after accepting a bribe to throw a football game, he was accepted by a gang that ran extortion and protection rackets and adopted the alias Flint Marko.
He soon became very successful in the New York criminal underworld, but was arrested, convicted, and forced to spend many years in solitary confinement. Upon his released he discovered that his long time girlfriend Marcy Conroy had left him for Vic Rollins, another member of his gang. In a rage he got revenge on Rollins and started a lone citywide crime spree. Marko was captured and placed in a maximum-security wing at Ryker's Island prison but escaped through an unguarded drainage tunnel. With the FBI and police on his tail, Marko traveled south and sought refuge in a place where he was unlikely to be found: an atomic testing site near Savannah, Georgia. As he rested on a nearby beach, the experimental reactor's steam system exploded, bombarding him with a massive dose of radiation and apparently bonding his body with the sand. Awakening after a brief period of unconsciousness, Marko discovered his newly acquired ability to transform into a sand-like substance he could manipulate and reshape at will. Now easily able to elude authorities, the Sandman was born.
|Pure Sand Sandman|