A federal judge on Wednesday granted a US government request to drop drug charges against former Mexican defence minister Salvador Cienfuegos and return him to Mexico, a move Mexico said would restore trust in the countries' severely strained security ties.
The dismissal came one day after a surprise announcement by US Attorney General William Barr and Mexican Attorney General Alejandro Gertz Manero that the US case would end, just one month after being announced.
"Although these are very serious charges against a very significant figure, and the old adage 'a bird in the hand' comes to mind, I have no reason to doubt the sincerity of the government's decision," US District Judge Carol Bagley Amon said at a hearing in Brooklyn, New York.
Cienfuegos, 72, was Mexico's defence minister from 2012 to 2018 under former President Enrique Pena Nieto.
He was flown back to Mexico later on Wednesday, according to a statement from Gertz Manero's office later on Wednesday.
Mexico's security establishment
The statement added that Cienfuegos, who arrived in a business suit, was formally informed that Mexican prosecutors have launched an investigation in which he is involved and based on evidence provided by the US government.
He was then released.
His arrest shook Mexico's security establishment, to which Cienfuegos has maintained close ties, and prompted President Andres Manuel Lopez Obrador's government to threaten a review of agreements letting US Drug Enforcement Administration agents operate in the country.
Seth DuCharme, the Acting US Attorney in Brooklyn, said his office "stands behind its case" against Cienfuegos but that the "broader interest" in maintaining cooperation between US and Mexican law enforcement was more important.
Wednesday's dismissal was without prejudice, meaning the US government could charge Cienfuegos again. Mexico said its own case so far was based solely on evidence provided by the US.
Speaking in Spanish, Cienfuegos told the judge he agreed to be moved to Mexico and did not expect to face persecution there.
His lawyer Edward Sapone said he expected the retired army general to be returned to Mexico on Wednesday, and later to his family.
"Today is a day of justice, because today there are no charges against him, either here or in Mexico," Sapone told reporters after the hearing.
Mike Vigil, a former DEA chief of international operations, said the dismissal sent "shockwaves" through that agency, where he remains in contact.
He also expressed scepticism Mexico would prosecute Cienfuegos, and suggested the dismissal was a "gift" from US President Donald Trump to reward Lopez Obrador for not recognising Joe Biden as US president-elect.
Cienfuegos' arrest, at Los Angeles International Airport, made him the first Mexican former military chief taken into US custody for drug-related crime in Mexico.
Flurry of frantic calls
While in office, Cienfuegos had worked closely with US authorities and become a leading Mexican figure fighting that country's drug war.
But US prosecutors said Cienfuegos abused the power of his office to protect a faction of the Beltran-Leyva cartel, while ordering operations against rival gangs.
Cienfuegos had pleaded not guilty to drug and money laundering conspiracy charges.
Mexican Foreign Minister Marcelo Ebrard said Cienfuegos' arrest damaged the trust needed for cooperation to fight drug gangs, though Wednesday's dismissal could help ease tensions.
"You can't have close cooperation with all of Mexico's institutions, and do this at the same time," Ebrard said. "You have to choose."
Cienfuegos' arrest came without warning to Mexico, and set off a flurry of frantic calls between Barr, DEA Acting Administrator Timothy Shea and Mexican officials.
David Shirk, global fellow for the Woodrow Wilson Centre for International Scholars, called the dismissal a "slap in the face" to many in US law enforcement.
"A lot of people probably put their lives on the line to bring Cienfuegos to justice," he said.
"The dismissal sends a message to law enforcement and organised crime groups that the US government is not serious about its commitment to the war on drugs."
Cienfuegos' arrest came 10 months after US prosecutors charged Mexico's former top public security chief, Genaro Garcia Luna, with taking bribes to protect the Sinaloa drug cartel once run by drug lord Joaquin "El Chapo" Guzman.
Garcia Luna has pleaded not guilty.