Notorious drug lord Rafael Caro Quintero, convicted for the torture and murder of a US anti-narcotics agent in 1985, has been arrested in Mexico.

But the coup came at a heavy price after a law-enforcement helicopter used in the mission crashed, killing 14 military personnel.

Mexican marines flushed out Caro Quintero with a bloodhound in a far-flung corner of the northwestern state of Sinaloa, one of Mexico’s drug-trafficking heartlands, before the Black Hawk chopper came down as it was about to land further south.

Caro Quintero rose to prominence as a co-founder of the Guadalajara  cartel, one of Latin America’s most powerful drug trafficking organisations during the 1980s, and had been among the most prized targets for US officials.

He was captured in San Simon in the Sinaloa municipality of Choix after a military-trained bloodhound named Max found him in shrubland, the navy said.

US pressure

The arrest comes after pressure from the United States, according to a Mexican official, and in the same week President Andres Manuel Lopez Obrador met with Joe Biden in Washington.

Lopez Obrador said on Twitter the navy would investigate what brought down the helicopter in the city of Los Mochis, Sinaloa.

Caro Quintero spent 28 years in prison for the brutal murder and torture of former US Drug Enforcement Administration (DEA) agent Enrique ‘Kiki’ Camarena, one of the most notorious killings in Mexico’s bloody narco wars.

The events, dramatised in the 2018 Netflix series Narcos: Mexico, led to a nadir in US-Mexico co-operation in a five-decade “war on drugs”.

Caro Quintero has previously denied involvement in the killing of Camarena. He was released in 2013 on a technicality by a Mexican judge, embarrassing the previous government.

He quickly went underground and returned to trafficking as part of the Sinaloa cartel, according to US officials, who put him on the FBI’s Top 10 most wanted fugitives list and slapped a $US20 million ($A29 million) bounty on his head.

Last year, he lost a final appeal against extradition to the United States.

‘One of the most important captures’

“It is probably one of the most important captures of the last decade in terms of importance to the DEA,” Mike Vigil, the DEA’s former chief of international operations, said.

US Attorney-General Merrick Garland said he would seek Caro Quintero’s immediate extradition.

“There is no hiding place for anyone who kidnaps, tortures, and murders American law enforcement,” Garland said in a statement.

“We are deeply grateful to Mexican authorities for their capture and arrest of Rafael Caro Quintero.”

Before extradition, Caro Quintero will be held in Altiplano prison in the state of Mexico, Mexican prosecutors said.

The penitentiary is notorious as the one from which his old Sinaloa cartel associate Joaquin ‘El Chapo’ Guzman escaped in 2015.

While the 69-year-old Caro Quintero is no longer considered a major player in international drug trafficking, the symbolic impact of his capture is significant.

The arrest points to significant co-operation between the United States and Mexico despite recent clashes over security, security expert Alejandro Hope said.

“This type of capture is unthinkable without the participation of the DEA,” he said.

Former DEA official Vigil said: “This will hopefully start to mend the frayed relationship between the United States and Mexico in terms of combating drug trafficking.”

-AAP