MEXICO CITY — The former mayor of a southern Mexico town where 43 students were abducted and disappeared in 2014 has been cleared of a kidnapping charge in the case, President Andrés Manuel López Obrador confirmed Wednesday.

José Luis Abarca, who will remain in prison for other crimes, had been considered one of the key figures in the students’ disappearances on Sept. 26, 2014 in Iguala.

The students from a rural teachers’ college at Ayotzinapa had hijacked buses — a common method for students from poor schools to obtain transportation — and were in Iguala that day. Iguala municipal police were among the first authorities to stop the buses and take the students off. More than eight years later, only small bone fragments of three of the students have been recovered and positively identified.

Investigations have been riddled with flaws, and courts have tossed out cases against other potential suspects. Some charges didn’t hold up because evidence was obtained through torture.

While the motive remains unclear, investigators have shown that local, state and federal authorities, including the military, were involved, as well as members of the Guerreros Unidos organized crime gang. A theory that Abarca ordered their abduction for political reasons was discarded; a leading hypothesis now is that the killings were somehow connected to heroin trafficking in the area.

In addition to being cleared of kidnapping charges, Abarca was absolved this month of an organized crime charge because prosecutors did not prove he belonged to Guerreros Unidos. A judge, however, sentenced Abarca to 92 years in prison for several unrelated aggravated kidnappings that happened a year before.

Despite the symbolism of Abarca no longer being charged in the students’ kidnapping, López Obrador said Wednesday that the court’s decision does not affect efforts to achieve justice. “We continue the investigation and we are not going to fail to keep our promise” to arrive at the truth, he said.