There is a comic book called "Visionaries", very non-canon, even for the extended universe stuff... think of it as a sort of "What If..." book.
In it, there's a story in which Maul comes back with a mechanical lower body to take revenge on Obi-Wan. He tells how he followed Obi's trail across Kamino, Geonosis, Mustafar etc. When he talks about getting information from a scrap dealer in Mos Espa, you see a picture of a decapitated Watto.