(CBS News) WASHINGTON -- Mexico's most notorious drug lord has been released from prison on a technicality. Rafael Caro Quintero was convicted more than a quarter of a century ago in a kidnapping and murder of a U.S. drug enforcement agent.
Sixty-year old Caro Quintero apparently walked out of a Mexican prison a free man, in the middle of the night with no cameras present. A court overturned his conviction saying he was tried in the wrong court back in 1985 -- federal instead of state -- for the murder of U.S. drug enforcement agent Enrique Camarena.
The release caught U.S. officials by surprise -- they heard about it from the Mexican media.
"We are extremely disappointed," said James Capra, chief of operations for the Drug Enforcement Administration, "and more than that, we are angry. We are mad. This is personal. Never did we think this was gonna happen."
Known as the godfather of Mexican drug cartels, Caro Quintero is on DEA's most wanted list. The agency said while in prison, he continued to work with the Sinaloa cartel, the largest in Mexico, and launder drug money.
Agent Camarena was working undercover when he exposed Caro Quintera's massive marijuana operation. The bust is said to have cost Caro Quintero and his associates $8 billion in lost sales.
Caro Quintera ordered Camerana's kidnapping. His body -- showing evidence of torture -- was found a month later in a shallow grave.
"We want him caught now," said Capra. "Right now we want him caught. He has no right to be walking free anywhere. Not in Mexico, not any place in the United States."
One U.S. official told CBS News that federal authorities in Mexico may not have known about the state court's release -- and that when someone like Caro Quintera walks free, it usually means millions of dollars in bribe money have changed hands somewhere.