According to historian Robert M. Utley, Robert Martin was a member of the Jesse Evans gang of outlaws in New Mexico during the mid- to late 1870s. Billy the Kid briefly joined this group before going to work for John Tunstall. Evans's gang, a loose-knit consortium of desperadoes known as "The Boys", ended up fighting against the "Regulators" during the Lincoln County War. Because of the time frame, the location, and his friendship with Martin, Curly Bill Brocius may have been a member of the Evans gang, as well.