NEW YORK -- A Mexican drug lord notorious for his role in a U.S. drug enforcement agent's brutal 1985 murder was arraigned on sweeping drug-trafficking charges in New York on Friday. The arraignment of the drug lord, Rafael Caro Quintero, a founding member of the Sinaloa Cartel, came a day after he was transferred to the United States from Mexico in a move that potentially signaled a new era of cooperation between the two countries. Caro Quintero was arraigned in U.S. District Court in Brooklyn along with Vicente Carrillo Fuentes, a former leader of the Juarez Cartel. Caro Quintero, 72, was charged in a superseding indictment in 2020 with smuggling thousands of kilograms of illegal drugs across the U.S. border as well as with a four-decade effort to murder his rivals. Carrillo Fuentes, 62, was charged in a separate indictment with similar crimes from 1990 to 2014. Both pleaded not guilty and were ordered held without bail. (BEGIN OPTIONAL TRIM.) "For decades, Rafael Caro Quintero and Vicente Carrillo Fuentes have flooded the United States and other countries with drugs, violence, and mayhem, killing so many in their quest for power and control," John J. Durham, the acting U.S. attorney for the Eastern District of New York, said in a statement. (END OPTIONAL TRIM.) Saritha Komatireddy, an assistant U.S. attorney, said in court that Caro Quintero and his associates had "pioneered the Mexican drug-trafficking industry." The men appeared before Magistrate Judge Robert M. Levy a day after Mexican authorities turned them and 27 other top drug-cartel operatives over to their American counterparts in an extraordinary move. The transfer was widely seen as a sign of Mexico's willingness to increase its cooperation with the U.S.' plans to crack down on its criminal mafias. President Donald Trump and his allies have pressured Mexico's president, Claudia Sheinbaum, with threats of tariffs on her country's goods and suggestions that the United States might take military action in Mexico if officials there did not work to stem the flow of drugs. But while the handovers of Caro Quintero and Carrillo Fuentes on Thursday came against that backdrop, they were also the product of highly sensitive negotiations between U.S. and Mexican officials that unfolded over several weeks, aided by American experts with deep experience in dealing with the cartels, according to a person familiar with the matter. Bringing Caro Quintero, in particular, to the United States has been an obsession for U.S. officials since long before Trump became fixated on defeating the cartels. And as word of the arraignments spread in law enforcement circles, federal agents and prosecutors, along with retired colleagues who had worked on cases connected to Caro Quintero, hastily made plans to travel to the Brooklyn federal courthouse. The arraignments took place in the building's largest courtroom, which was packed with reporters, lawyers and more than 100 drug enforcement agents, including some who sat in the jury box. Caro Quintero was led into the proceeding in handcuffs that had belonged to Enrique Camarena, the undercover Drug Enforcement Administration agent whom he was convicted of murdering. Komatireddy said that the agents were in the courtroom to "honor the memory of one of their own." She said the state may seek the death penalty for Caro Quintero. Caro Quintero and a second man were convicted in Mexico in 1989 of murdering Camarena, who was known as Kiki, four years earlier. Both defendants were sentenced to 40 years in prison in the killing; convictions on other charges that included kidnapping and drug trafficking stretched the sentences to more than 100 years apiece. The gruesome killing of Camarena, whose body was found mutilated and wrapped in a plastic bag on a ranch southeast of Guadalajara, was a seminal moment in U.S.-Mexico relations. It is considered to have accelerated the war on drugs, intensifying both countries' efforts to eradicate the cartels and increasing America's involvement in targeting the organizations' leaders. The wound left by Camarena's murder was reopened in August 2013, when Caro Quintero was released from prison in the middle of the night after serving only 28 years of his sentence, thanks to a legal loophole. The United States asked Mexico to rearrest him, but he evaded authorities for nine years before being captured in Sinaloa in 2022. "He was a fugitive hiding in the jungles and mountains of Sinaloa, hoping we would forget," Komatireddy said. "But justice never forgets." The transfer to the United States of Caro Quintero and the others took place not under the long-standing extradition treaty between the two countries, but rather in response to Trump's recent order designating six drug cartels as foreign terrorist organizations, Attorney General Pam Bondi said in a statement Thursday night. The order allowed for the men to be sent across the border without protracted court proceedings in Mexico. It also opened the possibility that federal prosecutors in the United States could seek terrorism and death penalty charges against them, Bondi said. In a news release announcing the transfers, Karoline Leavitt, the White House press secretary, called Caro Quintero "one of the most evil cartel bosses in the world." The Sinaloa Cartel, the indictment says, employed vicious hit men known as sicarios who exacted brutality on anyone who stood in their path. While Caro Quintero was the focus of attention in court Friday, prosecutors also arraigned Carrillo Fuentes, a significant figure in his own right. Carrillo Fuentes, who is known as El Viceroy, was a longtime leader of the Juarez Cartel. He took over the border gang from Amado Carrillo Fuentes, his older brother, who died unexpectedly in 1997 while having plastic surgery. The younger Carrillo Fuentes was first charged in Brooklyn in 2009 in an indictment that was updated 10 years later. It accuses him of smuggling thousands of kilograms of cocaine into the United States and conspiring to murder his organization's rivals. Until 2004, Carrillo Fuentes and the Juarez Cartel were closely allied with the Sinaloa Cartel, which was run at the time by infamous drug lords Joaquín Guzmán Loera, better known as El Chapo, and Ismael Zambada García, who is also known as El Mayo. But after bitter disputes over turf and trust, the Juarez organization split with Sinaloa, and the two criminal groups fought a bloody battle for control of Juarez, resulting in one of the goriest urban conflicts in the history of the drug war. Mexican authorities arrested Carrillo Fuentes in 2014 and tried, convicted and ultimately sentenced him to 28 years in prison. (STORY CAN END HERE. OPTIONAL MATERIAL FOLLOWS.) On Friday, Kenneth Montgomery, a lawyer for Carrillo Fuentes, urged the judge to consider the political climate in Latin America. "This man comes from a part of the world that's destabilized," Montgomery said, citing a book about the impact of European colonialism on the region. The U.S. attorney's office for the Eastern District of New York has a long history of pursuing Mexican cartels and their leaders, including Caro Quintero's organization and his associates. Guzmán was prosecuted in the Eastern District, where he was convicted on a vast set of criminal-enterprise charges and sentenced to life in prison in 2019. The office is currently handling the case against Zambada García, who will go on trial in Brooklyn after being abducted in Mexico over the summer by one of Guzmán's sons and forcibly flown across the border into U.S. custody. In 2023, Ismael Quintero Arellanes, whom prosecutors have said is Caro Quintero's nephew and right-hand man, was extradited and arraigned in Brooklyn federal court on drug trafficking and weapons charges. Craig Heeren, a former Eastern District deputy chief of national security and cybercrime, said the arraignments Friday reflected the "aggressive and international focus" of the office. "The prosecutors at EDNY are tenacious and take the long view on their investigations," Heeren said. The office also secured the October 2024 conviction of Genaro García Luna, Mexico's former top law enforcement official, who was sentenced to 38 years in prison for taking millions of dollars in bribes from the Sinaloa Cartel. This article originally appeared in The New York Times.