MEXICO CITY >> Mexico said Monday it has arrested the former head of a federal anti-kidnapping unit in connection with the disappearance of 43 students in 2014.

Gualberto Ramírez was head of the anti-kidnapping unit for the attorney general’s office when the students from the Ayotzinapa teachers college in southern Mexico went missing.

Assistant Interior Secretary Alejandro Encinas wrote that Ramírez faces charges of disappearance, torture and conspiracy for the botched investigation into the abductions, which are defined as “disappearances” under Mexican law because only remains of three of the victims have been identified.

Security forces abducted the students from buses in the city of Iguala on Sept. 26, 2014, and turned them over to a local drug gang, which apparently killed and burned them.

Encinas also wrote in his Twitter account that eight soldiers detained in the case last week have been charged by civilian prosecutors with disappearance. The soldiers are being held in a military prison, and could continue there.

Recent revelations implicate the military in the disappearances, but the motive for the students’ abduction remains unclear, though there is growing evidence it may have involved police and military collusion with drug traffickers.

Initial investigations into the alleged perpetrators were so botched with torture, mishandling of evidence, coercion and forced confessions that many of the charges against the suspects were later dismissed.