Benicio del Toro has joined the documentary “The Rise and Fall of the Brown Buffalo” as its executive producer, Variety has learned exclusively.

Directed by Phillip Rodriguez, the film explores the life of Oscar Zeta Acosta, who was a firebrand Chicano lawyer, writer, activist, and the real-life inspiration behind Hunter S. Thompson’s Dr. Gonzo in the 1971 novel “Fear and Loathing in Las Vegas: A Savage Journey to the Heart of the American Dream.”

Del Toro portrayed Dr. Gonzo opposite Johnny Depp’s Raoul Duke in director Terry Gilliam’s 1998 “Fear and Loathing in Las Vegas,” then won an Academy Award for “Traffic” in his next role. Del Toro also executive produced indie films “Lovesickness” in 2007 and “Viva” in 2015.

“We are ecstatic to have Benicio nurturing this project in his role as executive producer,” Rodriguez said. “Few people can speak to Acosta’s humanity and complexity like Benicio, who interpreted him for the big screen with such brilliance. It’s really a natural fit.”

Acosta was an attorney, politician and author during the early 1970s and wrote the novels “Autobiography of a Brown Buffalo” and “The Revolt of the Cockroach People.” Acosta disappeared in 1974 during a trip to Mexico and was never found.

“The Rise and Fall of the Brown Buffalo” uses archival footage with dramatized recreations and interviews. It also explores issues of racial identity, criminal justice, politics, and media representation that defined Acosta’s legacy.The documentary premieres on March 23 as a Voces special on PBS.

Major funding for “The Rise and Fall of the Brown Buffalo” is provided by The Corporation for Public Broadcasting. Additional funding is provided by Latino Public Broadcasting and California Humanities. The film is produced Rodriguez’s Los Angeles-based production company, City Projects, LLC.

Rodriguez’ documentary “Ruben Salazar: Man in the Middle” won best documentary at the 2014 San Antonio CineFestival and the 2014 Denver XicanIndie Festival.