Infamous drug lord Rafael Caro Quintero, who was behind the killing of a U.S. DEA agent in 1985, has been captured by Mexican forces nearly a decade after walking out of a Mexican prison and returning to drug trafficking.

Caro Quintero walked free in 2013 after 28 years in prison when a court overturned his 40-year sentence for the 1985 kidnapping and killing of U.S. Drug Enforcement Administration agent Enrique "Kiki" Camarena.

The brutal murder marked a low point in U.S.-Mexico relations. The former leader of the Guadalajara cartel had since returned to drug trafficking and unleashed bloody turf battles in the northern Mexico border state of Sonora.