Federal prosecutors in Mexico have charged a former state prosecutor with treason for allowing US agents to join a raid on a suspected drugs lab in April without proper authorisation.
César Jáuregui Moreno served as attorney general of the northern border state of Chihuahua from 2023 to this year.
The involvement of Americans came to light after two US agents said to have worked for the CIA died in a car crash in Chihuahua along with two Mexican law enforcement officers.
Attorney General Ernestina Godoy Ramos said Jáuregui had allowed foreign agents to carry out activities reserved for Mexican authorities and had failed to share information. Jáuregui has denied the allegations.
The former prosecutor, who is a member of the conservative opposition PAN party, was arrested at the weekend. A court hearing is scheduled for Saturday.
A judge must still determine whether there is enough evidence to proceed with the case, Reuters news agency reports.
Jáuregui also faces state-level charges in Chihuahua, including of abuse of public office. In a court hearing for those charges on Sunday, he denied that he instructed or consented to the involvement of US agents in the operation.
Mexican President Claudia Sheinbaum has come under pressure from US President Donald Trump to crack down on drug trafficking but has repeatedly declined offers of US-led counter-narcotics operations in the country.
She has been adamant that foreign officials can only operate on Mexican soil if given prior clearance by the federal government, and has insisted the Latin American nation’s sovereignty should not be breached.
The crash occurred on 19 April, when a convoy returning from an operation targeting suspected methamphetamine labs in a remote, mountainous area veered off the road and plunged into a ravine.
Two members of the Chihuahua State Investigation Agency were killed along with the Americans, officials said.
At the time, in his capacity as state attorney general, Jáuregui told a news conference that the Americans had been “instructor officers” from the US embassy engaged in “training work as part of the general and normal exchange we have with the US authorities”.
US media have reported that the two individuals worked for the CIA as part of an expanded effort to combat narcotics trafficking in the region.
