For more than a decade, Genaro García Luna was the square-jawed public face of Mexico’s war against its biggest criminal mafia: the Sinaloa drug cartel.
While leading the country’s version of the F.B.I., from 2001 to 2005, he personally took down top narco-traffickers like Arturo Guzmán Loera, the brother of Joaquín Guzmán Loera, the infamous drug lord known as El Chapo.
Over the next six years, as Mexico’s public security secretary, he used technology and gloves-off might to capture other cartel figures. And in that cabinet-level role, Mr. García Luna helped the president at the time, Felipe Calderón, launch an aggressive battle against drug cartels that spawned a new wave of violence across the country.
But all the while, amid the headlines and acclaim from partners in Washington, Mr. García Luna was leading a double life, American prosecutors say. Despite his public image as a lawman, they maintain, he was secretly taking bribes from the same drug gang he had a reputation for pursuing.
On Tuesday, more than three years after his arrest near Dallas, Mr. García Luna will go on trial in Federal District Court in Brooklyn, accused of being part of a continuing criminal enterprise.
In exchange for years of graft, prosecutors say, he helped the cartel’s traffickers to safely move their products into the United States, avoid scrutiny by Mexican law enforcement and, at times, carry out brutal attacks against their rivals.
The trial, which is expected to last eight weeks, is a kind of sequel to the El Chapo trial, a blockbuster proceeding that resulted in a conviction in 2019 in the same federal courthouse. Over the course of three months, it delved into the Sinaloa drug cartel’s astonishing logistics, its darkly violent tactics and its ever-shifting political alliances.
The García Luna trial will feature several of these aspects: As many as a dozen cartel witnesses are expected to take the stand and tell the jury that the defendant, among other things, took suitcases full of cash from Sinaloa operatives.
Since then, Mexico’s former top law enforcement official has become a symbol of the nation’s broken police force, used by Andrés Manuel López Obrador, Mexico’s president, to justify his growing reliance on the military to combat cartel violence.
The case against Mr. García Luna could further implicate two former top-ranking police officials who were charged with him but remain in Mexico: Luis Cárdenas Palomino and Ramón Pequeño García.
“The García Luna case is like a trunk full of secrets that could be made public,” Mr. Guerrero said. “It seems like we’re going to learn a lot of things we had no idea about.”
Among those most anxious to learn the details of the investigation, it seems, is Mexico’s president. Mr. López Obrador has repeatedly stressed how crucial it is for the media to closely cover the case and for the public to learn about it. He even had his foreign minister explain, in a recent news conference, the process of jury selection in the trial.