According to the San Francisco Chronicle, police believe the body is that of Omar Sharif Allah because of tattoos and other information.
They say Allah disappeared in October 2007.
City park crews found a human leg while cleaning out a homeless encampment.
Police say the body appeared to have been buried from more than a year. Investigators say an official identification of the remains is on hold pending analysis of dental records and other evidence.
No arrests have been made in Allah's disappearance and officials don't know how he may have died.