Willie Boy was a Chemehuevi-Paiute man who, in 1909, killed the father of a woman named Carlota — referred to as Lola in the film — following a conflict over their relationship. Under tribal custom, the killing allowed Willie to claim Carlota as his wife. Under California law, it was murder, and Deputy Sheriff Cooper led a posse into the desert after him. The chase cut through Morongo Valley and into the rugged terrain near what the film calls Ruby Mountain. Carlota was found shot in the back in an area known as The Pipes in northwest Yucca Valley. Willie Boy was blamed for her death. But a 1994 forensic analysis of the autopsy evidence concluded the bullet had traveled from too great a distance to have been fired by Willie, pointing instead toward the posse. Willie Boy died alone on Ruby Mountain, choosing death over capture. He wore a ghost shirt.

The 1969 film adaptation of Harry Lawton's 1960 book was written and directed by Abraham Polonsky — whose name had been absent from film credits for twenty-one years. Polonsky had been blacklisted after refusing to cooperate with the House Un-American Activities Committee, unable to direct again after Force of Evil in 1948. Tell Them Willie Boy Is Here was his return. The casting placed Robert Redford as Deputy Cooper and Robert Blake as Willie, with Katharine Ross as Lola. The film shoots across the same desert landscape where the events unfolded: the Morongo Valley, the high rocky terrain of Ruby Mountain, the relentless Mojave sun that flattens distance and makes everything look both close and impossibly far.

The film operates simultaneously as a Western and a critique of Westerns — or rather, of the American myth-making that turns tragedy into entertainment. The final line, spoken by Deputy Cooper when told the people want to see Willie Boy's remains: "Tell them we're all out of souvenirs," lands differently knowing the real history behind it. Willie Boy and Carlota were real people. Carlota's actual name appears to have been Carlota, though various accounts called her Isoleta or Lolita. She was shot in the back, and the people most likely responsible for that were never held accountable. The film does not flinch from the ambiguity. After sixty years, neither does the desert where it happened.