Caro Quintero was freed from the Puente Grande prison in the western Mexican state of Jalisco on Friday morning, according to the state attorney general’s office.
“There are various factors, and among them the fact that he already served his time for drug trafficking,” a court official said in explaining the release.
Camarena was kidnapped, tortured and murdered in retaliation for his involvement in a number of successful drug busts.
At the time, the United States was furious at a perceived lackluster effort to catch Camarena’s killer and the episode marked a low point in U.S.-Mexico relations. Caro Quintero was caught in Costa Rica in 1985.
His release raises the possibility of a renewed tussle between the two countries over the possible extradition of the aging drug lord.