What happens to the money when it gets there? The cartel employs professional money launderers who specialize in drug proceeds, and according to Robert Mazur, a former D.E.A. agent who infiltrated the Colombian cartels, the fee for fully scrubbing and banking illicit proceeds may run Sinaloa more than 15 cents on the dollar. But a great deal of the cartel’s money remains in cash. In the early 1990s, a Sinaloa accountant sent planeloads of U.S. currency to Mexico City in suitcases holding $1 million each. When Miguel Angel Martínez worked for Chapo, the kingpin would test his loyalty, adding an extra $200,000 to one of the suitcases to see if Martínez would pocket it. “Eight suitcases, compadre, so that is $8 million,” he would say. (Martínez never fell for the trick.) A sizable share of the cash is devoted to paying bribes, and some is sent to Colombia to purchase more product, because drugs offer a strong return on investment. “Where would you put your money?” the former Cisen officer Alejandro Hope asked me with a chuckle. “T-bills? Real estate? I would put a large portion of my portfolio in cocaine.”

Even so, the business generates such volumes of currency that there is only so much you can launder or reinvest, which means that money can start to pile up around the house. The most that Martínez ever saw at one time was $30 million, which just sat there, having accumulated in his living room. In 2007, Mexican authorities raided the home of Zhenli Ye Gon, a Chinese-Mexican businessman who is believed to have supplied meth-precursor chemicals to the cartel, and discovered $206 million, the largest cash seizure in history. And that was the money Zhenli held onto — he was an inveterate gambler, who once blew so much cash in Las Vegas that one of the casinos presented him, in consolation, with a Rolls-Royce. “How much money do you have to lose in the casino for them to give you a Rolls-Royce?” Tony Placido, the D.E.A. intelligence official, asked. (The astonishing answer, in Zhenli’s case, is $72 million at a single casino in a single year.) Placido also pointed out that, as a precursor guy, Zhenli was on the low end of the value chain for meth. It makes you wonder about the net worth of the guy who runs the whole show.

In 2008, the Flores twins were indicted in Chicago and began secretly cooperating with law enforcement. The following year, one of their Sinaloa contacts — a debonair young trafficker named Jesús Vicente Zambada Niebla, or Vicentillo — was arrested in Mexico and later extradited to Chicago. He will be the highest-ranking member of the cartel ever to face trial in the United States, and his favorite wholesale customers will be the star witnesses against him. In a surprise twist, Vicentillo (who is the son of Chapo’s partner, Mayo Zambada) has argued that he can’t be prosecuted — because even as he worked for Sinaloa, he was also a secret informant for the D.E.A.

There has been speculation in Mexico that the Calderón regime favors Sinaloa over the unhinged Zetas and has made a devil’s pact to lay off the cartel. It might be impossible to eradicate all the cartels in Mexico, this theory goes, so the government has picked a favorite in the conflict in the hope that when the smoke clears, a Sinaloa monopoly might usher in a sort of pax narcotica. A 2010 National Public Radio investigation of Mexican arrest statistics found that Sinaloa had suffered conspicuously fewer arrests than had its peers, though this could simply be evidence of triage on the government’s part rather than proof of a conspiracy. Calderón vehemently denies any charges of favoritism, and his administration has arrested or killed several of Chapo’s key deputies in the last few years. (My repeated requests for interviews with relevant officials in Mexico were denied.)

The suggestion that the D.E.A. might have made a deal with a high-ranking Sinaloa figure is new, however. In the past, Chapo has occasionally authorized employees to provide information to American law enforcement. Fierro Méndez, the Juárez cop, described a system in which junior traffickers would walk into U.S. Immigration and Customs Enforcement and announce their willingness to become informers — then feed the Americans intelligence about rival cartels, thereby using law enforcement to eliminate their competitors. U.S. officials allow that there were discussions between the D.E.A. and Vicentillo, but they deny that any quid pro quo was in place.

The trial, which is scheduled for October, should shed significant light on Sinaloa’s logistical apparatus — provided the witnesses can stay alive until then. Recently, a career criminal named Saul Rodriguez testified that Vicentillo solicited his help at the Metropolitan Correctional Center in downtown Chicago, where they were both being held, in an effort to have the Flores twins assassinated. Authorities have expressed concern that the cartel might undertake a daring jailbreak to get Vicentillo out. They have also voiced the opposite worry — that Vicentillo will himself be killed. A request by the trafficker’s attorneys that he be permitted to exercise outdoors raised concerns from prison officials, because the only open space at the prison is a fenced-in recreation area on top of the building, where Vicentillo could be picked off by a sniper. (He has since been moved to a more secure facility.)

It might seem far-fetched that the cartel would try to assassinate one of its own, the son of Mayo Zambada, no less. But Sinaloa guards its secrets ruthlessly. After Chapo’s friend Miguel Angel Martínez was arrested in 1998, four men came to kill him in prison, stabbing him repeatedly. In that assault, and another that followed, he sustained more than a dozen stab wounds, which punctured his lungs, pancreas and intestines. After the second attack, he was moved to another facility and kept in a segregated unit. This time, an assassin managed to get as far as the gate outside Martínez’s cell and chucked two grenades at the bars. Locked in with nowhere to run, Martínez could only cower by the toilet to shield himself from the blast. The roof caved in, and he barely survived. Asked later who it was that tried to have him killed, Martínez said that it was his compadre, Chapo Guzmán. “Because of what I knew,” he explained. (Today he is living in witness protection in the United States.)