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.

Trump designated drug cartels terrorist organizations and Mexico extradited 29 alleged members, one a suspect in a notorious DEA killing in 1985.

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.