U.S. offers $5-million reward for drug kingpin Rafael Caro Quintero, seen in prison in 2005, had served 28 years of a 40-year sentence when he was released from prison in Mexico. AFP/Getty Images / January 29, 2005 By Richard Fausset November 5, 2013, 7:50 p.m. MEXICO CITY - The U.S. State Department is offering a reward of up to $5 million for information leading to the arrest of Mexican drug lord Rafael Caro Quintero, who was convicted in the murder of a U.S. anti-narcotics agent in 1985, but vanished in August after a Mexican court freed him from prison on a technicality. Caro Quintero, 61, once one of Mexico's most powerful drug kingpins, was last seen walking out of a medium security prison in the state of Jalisco around 2 a.m. on Aug. 9 after serving 28 years of a 40-year sentence. An appeals court granted him freedom after controversially ruling that his federal case should have been handled in a state venue. The State Department's brief written announcement of the reward Tuesday was apparently an admission that Caro Quintero's whereabouts are unknown to U.S. officials, and perhaps to their Mexican counterparts as well. Caro Quintero has been indicted in the Central District of California on various federal felony charges, and the U.S. government formally requested his extradition a few days after he was freed. The request obliged Mexican authorities to launch a manhunt. The 1985 kidnapping, torture and slaying of Drug Enforcement Administration agent Enrique "Kiki" Camarena remains an open wound for the DEA, and Caro Quintero's gang has also been implicated in the killing of six other Americans. But the U.S. is also keen to continue its close working security relationship with the Mexican government under President Enrique Peña Nieto. The Mexican attorney general's office has appealed the appellate court's ruling. The Supreme Court is scheduled to take up the matter Wednesday - a purely intellectual exercise if Caro Quintero isn't found.