Sheriff Mayo was based in Arizona. He was in a coma as a result of being shot by James after he kidnapped Teresa, but was later killed while he was in prison.
La Fuerza: Mayo is introduced when he enters the diner that Teresa, James, and Pote are eating in and arrests a kitchen boy. He is later shown on the news and asked why he targets Hispanic people in his sweeps. After an attempt to take down Mayo by sending an incriminating video to a local reporter, Mayo kidnaps the reporter and kills him in front of James and Teresa. He leaves James behind to bury the reporter while he holds Teresa for ransom. At the exchange, James shoots Mayo, which lands him in a coma. He is ironically found and saved by an undocumented person.
El Carro: Mayo kills an Indian from Taza's tribe who betrays the transportation route to Phoenix. Mayo and his men disturb the transport operation which results in a chase and some lost merchandise.
El Diablo: Teresa meets with Mayo, James, and Pote at a bar. Mayo calls them the Four Horsemen of the Apocalypse and asks Teresa which one she thinks she is. Teresa thanks Mayo for putting Bedoya in the county jail. He says that he just saw which way the wind was blowing and made the smart choice. He says that it's kind of disappointing that she was once on her high horse with her heart bleeding over that kid in his jail, and now he's right there with her. He throws down a hundred dollar bill saying that everyone has their price, and I guess yours is Phoenix.
Later, Mayo meets with Pecas, promising him that his men will drive him to the border. Pecas hands him a bag of cash and tells Mayo that he expects to hear of Teresa's death within the next week. When Teresa, Pote, and James stride in, Mayo presses a gun to the back of Pecas's head. James kills Pecas. Mayo kneels down to remove Pecas's jewelry. He tells Teresa that he has a nice spot picked out for Pecas in the desert, right next to the reporter.
By that evening, the video of Mayo beating an inmate has gone viral. Theo Carson had Mayo arrested and sent to prison. A guard hands Mayo a flip phone, and Teresa tells him that she is War. The guard leads Mayo to a room with a group of inmates that are waiting for him. Mayo is pushed in and the phone falls to the floor as the inmates beat him to death. Teresa listens for a while, but soon hangs up.
- James: ... the good news is, he's for sale.
- Interviewer: The operation is being spearheaded by a man with a deplorable record of civil rights abuses. Sheriff Mayo, your response to those who say that you are unfairly targeting Mexicans during these sweeps.
- Mayo: You call it profiling, I call it common sense policing. And I'm doing the job that voters elected me to do.