William Hasley, a writer who co-wrote a book with Caitlyn Jenner, is identified as the hiker found dead on Los Angeles’ Runyon Canyon trail, according to multiple reports. He was 78. The articles say Hasley was found after collapsing on the popular hiking route and that his body was discovered last Saturday. Variety reports that Hasley worked as a screenwriter and has credits on television, including the series “The Smurfs.” It also says he co-wrote an inspirational book with Jenner. Other coverage identifies him as Jenner’s friend and biographer/ghostwriter. Variety further notes that Hasley was previously married to actress Robin Riker, known for “The Bold and the Beautiful.” The reports provide the identification but do not describe any suspected cause of death. Authorities have not been quoted in the provided excerpts, and the circumstances leading to his collapse are not detailed beyond the discovery on the trail.