Mexico drugs lord Caro Quintero's release angers US
The US has reacted angrily to the early release by a Mexico court of a drugs lord who served 28 years in prison for the kidnap and murder of a US agent.
The court cut short Rafael Caro Quintero's 40-year sentence for the 1985 killing of US Drug Enforcement agent Enrique Camarena.
It ruled that Caro Quintero, now 60, should have been tried in a state rather than a federal court.
The Drug Enforcement Agency said the move was "deeply troubling".
The murder strained US-Mexico ties and changed the war on drugs trafficking.
Caro Quintero is still listed as one of the DEA's five top international fugitives, and the US authorities believe he has been controlling drugs money from behind bars.
"DEA will vigorously continue its efforts to ensure Caro Quintero faces charges in the United States for the crimes he committed," said the agency in a statement.
Mexico's Attorney General Jesus Murillo Karam echoed those concerns, saying his office was analysing whether there were any charges pending against Caro Quintero.
One of three founding members of the Guadalajara Cartel, Caro Quintero had been arrested in Costa Rica amid a massive manhunt for cartel leaders.
The group was thought to be responsible for transporting the majority of the cocaine consumed in the US in the 1980s, the BBC's Will Grant reports from Mexico City.
Caro Quintero could have faced other charges or possible extradition to the US, but walked free early on Friday before media were notified.
The court did not clear Caro Quintero of Camarena's death, a move that would caused significant scandal in US law enforcement circles where the murdered operative is heralded as a hero, adds our correspondent.
Many analysts believe the Camarena killing represented a key turning point in the fight against drug trafficking in Mexico.
It broke up the Guadalajara Cartel into splinter groups, which formed the basis of today's powerful drug gangs.