Joaquin Murrieta (c. 1829 - c. July 25, 1853), also called the Mexican Robin Hood or the Robin Hood of El Dorado, was a famous figure in California during the California Gold Rush of the 1850s. Depending on the point of view, he was considered as either an infamous bandit or a Mexican patriot.
When Ben Cartwright enters the jail to visit Billy, he does so with his gun in his holster. The sheriff forgets to tell him to leave his gun outside the jail.