By Luc Cohen NEW YORK (Reuters) -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 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.

The Mexican drug kingpin who was brought to the United States on Thursday is accused in the 1985 kidnapping, torture and murder of DEA agent Enrique “Kiki” Camarena.