“Yeah, I killed that son of a bitch.” Martinez’s eyes, which McWhorter had found so friendly moments before, were now black and cold. “He said some bad stuff about my daughter. I stand up for my family. I don’t let anyone talk about my family.”

McWhorter was still trying to make sense of that when Martinez delivered a much bigger revelation: “I’ve killed over 35 men in my life.”

Martinez, who was born and spent most of his life in California, said that for three decades he had worked as a gun for hire, collecting debts and killing people across the United States. Police say that work was often for Mexican drug cartels, though in a few cases he also killed a few people just because they pissed him off. Martinez refused to say anything about the drug business, including whom he worked for or with. But he was more than happy to talk about bodies. And about his own prowess in killing. They called him El Mano Negra, he said — the Black Hand.

The dead were young and old, drug dealers and farm laborers, fathers and husbands. But always men. They were scattered across as many as 12 states, but his primary killing ground was Tulare County, a little-populated land of vast green fields and listless, sunblasted farm towns in California’s Central Valley, where Martinez had been born and raised.