The former attorney general of Mexico has been arrested in connection with the 2014 disappearance of 43 students.
Jess Murillo Karam, who oversaw the investigation into the atrocity, has been charged with forcible disappearance, torture, and obstructing justice.
The students vanished while on their way to a protest in Mexico City by bus through the city of Iguala.
Nothing is known about their fate other than bone fragments recovered from three of them.
On the evening of September 26, 2014, municipal police opened fire on buses carrying students, but what happened next is debatable.
Their mysterious disappearance caused global outrage and sparked widespread protests in Mexico against impunity and state complicity in organized crime.
Jesus Murillo Karam, who was arrested on Friday, was the leader of a contentious 2015 investigation into what happened to the students, which blamed members of a cartel for killing them and burning their bodies.
His findings, which were endorsed by then-President Enrique Pea Nieto, were criticized by independent experts and relatives of the missing students for errors and for failing to hold the armed forces accountable.
Mr Karam’s Institutional Revolutionary Party (PRI), which is no longer in power, accused those responsible for Friday’s arrest of being politically motivated in a tweet.
He is the highest-ranking government official to be arrested in connection with the students’ disappearance so far.
Investigators believe the students were apprehended by corrupt police officers and then handed over to a drug cartel, which mistook them for members of a rival gang before murdering them.
On Thursday, a truth commission appointed by current President Andrés Manuel López Obrador accused soldiers of bearing some responsibility for the massacre, if not directly, then through negligence.
“Their actions, omissions, or participation allowed the students’ disappearance and execution,” said Alejandro Encinas, the commission’s head and Mexico’s deputy interior minister, according to AFP.
