Kenneth Litwack, 71, checked himself into the Sierra Tucson facility in August. Four days later, he was reported missing.
Litwack's watch, wallet and cell phone were still in his room, but there was no sign of him.
Pima County's Medical Examiner's Office has confirmed that a badly decomposed body found near a stable on the center's property on Tuesday was Litwack.
Investigators said there was no sign of a crime. The cause of death has not been determined.