El Chapo escaped from a maximum-security prison and evaded many attempts at capture, often hiding out in the Sierra Madre. Clockwise from top left: Alfredo Estrella / AFP / Getty; Greg Mathieson / Mai / Mai / Time Life Pictures / Getty; Ronaldo Schemidt / AFP / Getty; Nikolai Golovanoff / Corbis; Artgraphixel / Shutterstock; Natrot / Shutterstock; Us DEA / Reuters; Chris Ratcliffe / Bloomberg / Getty; BSIP / UIG / Getty; Zimand / Shutterstock (AK-47); Ronaldo Schemidt / AFP / Getty (handgun)

One afternoon last December, an assassin on board a K.L.M. flight from Mexico City arrived at Amsterdam’s Schiphol Airport. This was not a business trip: the killer, who was thirty-three, liked to travel, and often documented his journeys around Europe on Instagram. He wore designer clothes and a heavy silver ring in the shape of a grimacing skull. His passport was an expensive fake, and he had used it successfully many times. But, moments after he presented his documents to Dutch customs, he was arrested. The U.S. Drug Enforcement Administration had filed a Red Notice with Interpol—an international arrest warrant—and knew that he was coming. Only after the Dutch authorities had the man in custody did they learn his real identity: José Rodrigo Arechiga, the chief enforcer for the biggest drug-trafficking organization in history, Mexico’s Sinaloa cartel.

To work in the Mexican drug trade is to have a nickname, and Arechiga went by the whimsically malevolent handle El Chino Ántrax. He supervised the armed wing of the Sinaloa—a cadre of executioners known as Los Ántrax—and coördinated drug shipments for the cartel’s leader, Joaquín Guzmán Loera, who was known as El Chapo, or Shorty. Arechiga was a narcotraficante of the digital age, bantering with other criminals on Twitter and posting snapshots of himself guzzling Cristal, posing with exotic pets, and fondling a gold-plated AK-47. Guzmán, who is fifty-seven, typified an older generation. Obsessively secretive, he ran his multibillion-dollar drug enterprise from hiding in Sinaloa, the remote western state where he was born, and from which the cartel takes its name. The Sinaloa cartel exports industrial volumes of cocaine, marijuana, heroin, and methamphetamine to America; it is thought to be responsible for as much as half the illegal narcotics that cross the border every year. Guzmán has been characterized by the U.S. Treasury Department as “the world’s most powerful drug trafficker,” and after the killing of Osama bin Laden, three years ago, he became perhaps the most wanted fugitive on the planet. Mexican politicians promised to bring him to justice, and the U.S. offered a five-million-dollar reward for information leading to his capture. But part of Guzmán’s fame stemmed from the perception that he was uncatchable, and he continued to thrive, consolidating control of key smuggling routes and extending his operation into new markets in Europe, Asia, and Australia. According to one study, the Sinaloa cartel is now active in more than fifty countries.

On several occasions, authorities had come close to catching Guzmán. In 2004, the Mexican Army descended on a dusty ranch in Sinaloa where he was holed up, but he had advance warning and fled along a rutted mountain track in an all-terrain vehicle. Three years later, Guzmán married a teen-age beauty queen named Emma Coronel and invited half the criminal underworld of Mexico to attend the ceremony. The Army mobilized several Bell helicopters to crash the party; the troops arrived, guns drawn, to discover that Guzmán had just departed. American authorities have no jurisdiction to make arrests in Mexico, so whenever D.E.A. agents developed fresh intelligence about Guzmán’s whereabouts all they could do was feed the leads to their Mexican counterparts and hope for the best. In Washington, concerns about the competence of Mexican forces mingled with deeper fears about corruption. A former senior Mexican intelligence official told me that the cartel has “penetrated most Mexican agencies.” Was Guzmán being tipped off by an insider? After a series of near-misses in which Chapo foiled his pursuers by sneaking out of buildings through back doors, officials at the U.S. Embassy in Mexico City took to joking, bitterly, that there is no word in Spanish for “surround.”

Guzmán developed “a Zorro-like reputation,” Gil Gonzalez, who pursued him in Mexico for the D.E.A., told me. In dozens of narcocorridos, the heraldic Mexican ballads that glorify traffickers, singers portrayed Guzmán as a country boy turned cunning bandit who had grown rich but not soft, his cuerno de chivo, or “goat horn”—Mexican slang for an assault rifle with a curved magazine—never far from his side.

Yet Guzmán himself remained maddeningly obscure. Only a few photographs of him circulated publicly. A famous series taken after an arrest in 1993 shows a stocky, dark-eyed, square-jawed young man standing awkwardly in a prison yard; he gazes at the camera with a shyness that seems at odds with his fearsome reputation. Chapo escaped eight years later, and had been on the run ever since. Because he might have had plastic surgery to alter his appearance, the authorities could no longer be sure what he looked like. One narcocorrido captured the predicament: “Only he knows who he is / So go looking for someone / Who looks just like him / Because the real Chapo / You’ll never see again.”

The authorities tried to track Guzmán by monitoring telephone lines. Narcotics smuggling necessitates regular phone communication between farmers and packers, truckers and pilots, accountants and enforcers, street dealers and suppliers. But traffickers at the top of the hierarchy maintain operational security by rarely making calls or sending e-mails. Guzmán was known to use sophisticated encryption and to limit the number of people he communicated with, keeping his organization compartmentalized and allowing subordinates a degree of autonomy, as long as the shipments kept running on time. “I never spoke to him directly,” one former Sinaloa lieutenant told me. “But I knew what he wanted us to do.”

The Sinaloa cartel is sometimes described as a “cellular” organization. Structurally, its network is distributed, and has more in common with a terrorist organization like Al Qaeda than with the antiquated hierarchies of the Cosa Nostra. When the cartel suffers the loss of a major figure like El Chino Ántrax, it can reconstitute itself—but not without a few phone calls among the leadership. At the D.E.A., which taps hundreds of phone lines and e-mail accounts associated with traffickers, the process of applying pressure to a criminal organization and then monitoring furtive attempts at outreach is known as “tickling the wires.” When El Chino Ántrax was arrested in Amsterdam, the cartel was still coping with two other high-level losses: in November, the twenty-three-year-old son of one of Guzmán’s closest associates was arrested while trying to cross the border in Nogales; in December, Mexican troops in a helicopter shot and killed another key cartel enforcer, on a stretch of highway by the Sea of Cortez.

As the cartel attempted to regroup, authorities on both sides of the border intercepted scores of phone calls, texts, and e-mails. They learned that Guzmán would soon be coming to Culiacán, the state capital of Sinaloa, for a meeting with his sons Alfredo and Iván—ascendant traffickers who were both close friends of El Chino Ántrax. The D.E.A. presented an intelligence dossier to authorities in Mexico, and in mid-January a special-forces unit of commandos from the Mexican Marines, or SEMAR, began to assemble at a forward operating base near the resort town of Los Cabos, along the southern tip of the Baja Peninsula. The marines, who are the Mexican equivalent of Navy SEALs, were joined by a small group of American advisers. Mexican authorities code-named the mission Operation Gargoyle. Its object was to capture Guzmán.