Rangers at Yosemite National Park arrested Pearce Allen Miller, 20, in the murder of a Sherman Oaks man whose decomposed body was found five months ago in Griffith Park. Los Angeles police said the victim, James William Warner, 28, was probably slain on Nov. 11, 1984--the same day his automobile was found ablaze on Mulholland Drive--but he remained unidentified for nearly two months after his remains were discovered by a hiker Jan. 13. Dental records finally established the identity of the body March 8, and a warrant was issued for Miller’s arrest March 21. Miller was arrested after police notified rangers that he was camping in the park. A police spokesman said Warner had withdrawn $1,000 from his bank on the day he was slain.