He explained his work to me during the first of several visits I have made to his mortuary. “Each different mutilation leaves a message,” he said. “The mutilations have become a kind of folk tradition. If the tongue is cut out, it means the person talked too much—a snitch, or chupro. A man who has informed on the clan has his finger cut off and maybe put in his mouth.” This makes sense: a traitor to a narco-cartel is known as a dedo—a finger. “If you are castrated,” Muñoz continued, “you may have slept with or looked at the woman of another man in the business. Severed arms could mean that you stole from your consignment, severed legs that you tried to walk away from the cartel.”

There are gradations within these barbarities. “Sometimes they are done by a medical student, sometimes by just a butcher. It’s the medical students who have something to say. They are the ones trying to speak to us. I look at a cut-off toe. How was it done? Was it done well? Was it done from the left or the right? If it was done well, exactly between the bones, the person is more dangerous. If a finger was wrapped up tight before it was cut, we know we are dealing with the medical student, employed by the cartel hierarchy. If it’s just hacked off, we’re dealing with a malandro, a petty criminal. You need to cut it properly if you are going to send it to the victim’s family, or the police.”

In some cases the message is very blunt and all too clear, such as the message delivered by the 12 festering bodies lined up outside the Valentín Gómez Farías elementary school, in Tijuana, one morning in September 2008. The victims were naked, or partially dressed, and all of them had been tortured. Most had their tongues cut out. This was a message sent directly to children, something for them to think about as they consider their future lives in the community: Don’t talk too much. “It was a warning, and it means what it means,” said the head teacher, Miguel Ángel González Tovar.

Other cases are more difficult. On a slab one day in the summer of 2009, Muñoz showed me the headless body of the once lovely Adriana Alejandra Ruiz Muñiz, a model and a cheerleader for the local soccer team, Xoloitzcuintles de Caliente. A video of her death had been found on the mobile phone of a man named José Carlos Meza Zepeda, who was detained. Meza Zepeda protested his innocence, but he also claimed that Adriana had been a chupra, furnishing Mexican authorities with information about one of the point men in Tijuana for the Sinaloa Cartel. Adriana had had her fingernails pulled out and her fingers broken during the interrogation, after which she was decapitated.

Muñoz considered two hypotheses about Adriana: “that this case could be the big narcos, as they say it is, or a crime specifically against a woman, a so-called crime of passion by a common criminal, for what passion is more wrathful and violent than that of a man towards a woman he is obsessed with and cannot have? And this is, actually, my inclination in this case. I’ve looked very carefully at how the fingers have been broken, and it has not been done very well—you could almost call it careless, or reckless, but when the narcos are torturing an informant, the tracks they leave are never careless. They would have sliced the fingers off at the joints, not merely crushed them, maybe so as to send them to someone.