(oops! sticky keyboard) read that: "Not Samuel? What makes you think so?"
The Bible does not support the idea of dead humans communicating with the living. Read Psalm 146:4 and Ecclesiastes 9:5.
Either the witch was possessed and being fooled by a demon, or she was just ripping Saul off. Read the account from the beginning of the chapter. There must have been a reason why Saul (apparently while he was in good with the Almighty), ran the mediums outta town.