Alleged drug cartel boss Rafael Caro Quintero, who spent decades in prison in Mexico for the murder of a U.S. drug enforcement agent, pleaded not guilty in a U.S. court on Friday to drug trafficking charges that could result in his execution.

Mexico has extradited notorious drug lord Rafael Caro Quintero and 28 other fugitive cartel members to the United States, according to the US Department of Justice. Caro Quintero, considered by Mexican authorities to be the founder of the Guadalajara cartel,

Mexico has sent drug lord Rafael Caro Quintero, who is wanted for the notorious killing of a U.S. DEA agent in 1985, to the United States with 28 other prisoners requested by the U.S. government, the Justice Department confirmed Thursday evening.