In the early 2000s, a top member of the Sinaloa drug cartel said he intercepted a rival organization’s shipment of cocaine as it passed through the Mexican state of Chiapas.
After the drugs had been taken to a warehouse, the member testified on Monday, one of the cartel’s bosses showed up with an unexpected guest: Genaro García Luna, who was then in charge of Mexico’s equivalent of the F.B.I.
An agreement had been reached, according to the cartel member, Sergio Villarreal Barragán. The cartel would take half of the profits from the sale of the two-ton load and Mr. García Luna would get the other half — or more than $14 million.
The account of the warehouse deal came on the first full day of Mr. García Luna’s corruption trial in Federal District Court in Brooklyn. In dueling opening statements, the government and the defense offered radically different descriptions of the defendant.
Prosecutors said that for more than a decade, Mr. García Luna led a double life, taking millions of dollars in bribes to protect the very traffickers he was supposed to be pursuing.
But his lawyers countered these arguments. They said that Mr. García Luna was what he has always claimed to be: an honest lawman who had helped the United States arrest top figures in the Sinaloa cartel. Those same criminals, the lawyers said, had now returned to seek revenge against him as government witnesses.
The trial, which could last as long as eight weeks, will present the jury with a stark choice: Was Mr. García Luna, the highest-ranking Mexican official ever to stand trial in a U.S. courtroom on drug trafficking charges, a scourge of the Sinaloa cartel or was he secretly a servant to it?
Along the way, the proceeding will take the jurors on a tour of the dizzying hall of mirrors that often exists inside the corridors of power in Mexico.
Philip Pilmar, a federal prosecutor, opened the government’s case by laying out the defendant’s professional biography.
He told the jury that Mr. García Luna entered public service in 1989 by working for C.I.S.E.N., a newly formed intelligence agency in Mexico. From 2001 to 2006, he served as director of the Federal Investigative Agency. Then, under former President Felipe Calderón, he was named Mexico’s public security secretary, a powerful cabinet-level position he held until 2012.
But all that time, Mr. García Luna, who is accused of being part of a continuing criminal enterprise, was betraying his colleagues and his country, Mr. Pilmar said.
“While entrusted to work for the Mexican people, he also had a second job, a dirtier job, a more profitable job,” Mr. Pilmar said. That job, he went on, was protecting the Sinaloa cartel’s vast shipments of cocaine and other drugs as they crossed the border to American consumers.
In his own opening statement, César de Castro, Mr. García Luna’s lead lawyer, told the jury that, despite the government’s claims, prosecutors had no definitive evidence of his client’s guilt and that the prosecution’s case would rely almost exclusively on witnesses from within the cartel itself. Many of those witnesses were men who Mr. García Luna had helped to arrest in Mexico and extradite to the United States, providing them a motive to testify against him.
“What better revenge,” Mr. de Castro said, “than to bury the man who led the war against the cartels.”
Mr. de Castro also pointed out that throughout his long career, Mr. García Luna worked closely with a who’s who of top U.S. officials in the State and Justice Departments, as well as in Congress and the White House.
To that end, he showed the jury an array of photos of his client posing with Eric Holder, a former attorney general, and Hillary Clinton, the onetime secretary of state; and shaking hands with President Barack Obama.
After the opening statements, the government called Mr. Villarreal Barragán, a former police officer who switched sides in the drug war and went to work for the cartel in about 2001.
A towering man known as El Grande, Mr. Villarreal Barragán told the jury that he was present several times when his boss, a cartel leader named Arturo Beltrán Leyva, gave bribes to Mr. García Luna, often at a safe house near a church in the southern section of Mexico City. The bribes, he said, typically amounted to $1 million or $1.5 million a month.
According to Mr. Villarreal Barragán, much of the money came from a pool of funds assembled by Mr. Beltrán Leyva and other cartel leaders like Joaquín Guzmán Loera, the drug lord known as El Chapo who was convicted at a trial in the same Brooklyn courthouse in 2019.
Over time, Mr. Villarreal Barragán told the jury, the bribes financed the services of federal police officers who worked for Mr. García Luna and who helped the traffickers expand their operations through vast swaths of Mexico.
“The payments grew as the cartel grew,” Mr. Villarreal Barragán said, “and without that support it would have been practically impossible.”
The trial is not the first time that Mr. García Luna has been publicly accused of corruption. More than a decade ago, Edgar Valdez Villarreal, a lieutenant to Mr. Beltrán Leyva known as La Barbie for his handsome looks, sent a letter to a newspaper in Mexico, accusing Mr. García Luna of having accepted bribes from him directly.
A spokesman for Mr. García Luna at the time denied the allegations and said they were an attempt to “publicly discredit” the Mexican authorities and “blackmail” them in exchange for privileges inside the federal prison where Mr. Valdez was being held.
Mr. Valdez may appear as a witness at the trial along with other top traffickers whom Mr. García Luna helped take into custody. Among them is Jesús Zambada García, who told the jury during Mr. Guzmán’s trial that he met with Mr. García Luna twice in a restaurant, each time delivering a briefcase stuffed with at least $3 million in cash.
It was that testimony, in 2018, that prompted prosecutors in Brooklyn to begin to build a case against Mr. García Luna, according to a person familiar with the matter who was not authorized to speak publicly. Federal agents in Houston had been working on their own case against him since about 2012, the person said, but were unable to persuade the Justice Department to file charges.
In his more than three hours on the stand, Mr. Villarreal Barragán told the jury that Mr. Beltrán Leyva considered Mr. García Luna a friend and once gave him a custom-made Harley-Davidson motorcycle as a gift.
He rattled off a long list of corrupt police officials who worked with the defendant, including Luis Cárdenas Palomino and Ramón Pequeño García, who are charged in the same case, but remain at large in Mexico.
During his testimony, Mr. Villarreal Barragán also implicated a former high-ranking police official, Edgar Millán Gómez, as being allied with a subset of the Sinaloa cartel run by Mr. Guzmán.
Mr. Millán was famously murdered by a cartel hit squad in 2008 at a moment when Mr. Guzmán’s faction of the cartel went to war with a faction led by Mr. Beltrán Leyva.