Zane Grey isn’t Altadena’s only cowboy author:  found this at the Texas State Historical Society website about Charles Siringo (1855-1928), who died in Altadena after a career as a cowboy, merchant, detective, and author.  As a Pinkerton agent, Siringo helped track “Billy the Kid,” whom he’d previously met in his cowboy days.  It’s an interesting life, and it’s detailed right here.  He’s buried at Inglewood Cemetery.  Here’s the wicki entry.

Cowboy actor L.Q. Jones portrayed Det. Siringo in the 1974 made-for-TV movie Mrs. Sundance (with Elizabeth Montgomery playing the Sundance Kid’s girlfriend, Etta Place).