Federal prosecutors arrested a former Mexican attorney general on charges he committed abuses in the investigation of the 2014 disappearances of 43 students.
Jesus Murillo Karam served as attorney general from 2012 to 2015, under then president Enrique Pena Nieto.
The office of the current attorney general, Alejandro Gertz Manero, said he was charged with torture, official misconduct and forced disappearance.
In 2020, Mr Gertz Manero said Mr Murillo Karam had been implicated in “orchestrating a massive media trick” and leading a “generalised cover-up” in the case.
The arrest came a day after a commission set up to determine what happened said the army bore at least partial responsibility in the case.
It said a soldier had infiltrated the student group involved and the army did not stop the abductions even though it knew what was happening.
Corrupt local police, other security forces and members of a drug gang abducted the students in the city of Iguala in Guerrero state, although the motive remains unclear eight years later.
Their bodies have never been found, though fragments of burned bone have been matched to three of the students.
Mr Murillo Karam, under pressure to quickly solve the case, announced in 2014 that the students had been killed and their bodies burned at a garbage dump by members of a drug gang.
He called that hypothesis “the historic truth”.
But the investigation included instances of torture, improper arrest and mishandling of evidence that has since allowed most of the directly implicated gang members to walk free.
The incident occurred near a large army base, and independent investigations have found that members of the military were aware of what was occurring.
The students’ families have long demanded that soldiers be included in the investigation.
On Thursday, the truth commission looking into the case said one of the abducted students was a soldier who had infiltrated the radical teachers’ college, yet the army did not search for him even though it had real-time information that the abduction was occurring.
It said the inaction violated army protocols for cases of missing soldiers.
The defence ministry has not responded to a request for comment.
The Institutional Revolutionary Party, which both Mr Murillo Karam and Mr Pena Nieto belonged to, wrote in its Twitter account that Mr Murillo Karam’s arrest “is more a question of politics than justice. This action does not help the victims’ families get answers”.
Mexican federal prosecutors previously issued arrest warrants for members of the military and federal police as well as Tomas Zeron, who at the time of the abduction headed the federal investigation agency, Mexico’s detective agency.
Mr Zeron is being sought on charges of torture and covering up forced disappearances. He fled to Israel, and Mexico has asked the Israeli government for help in his arrest.