Mexican authorities say they have detained the former police chief of a southern city where 43 students disappeared two years ago.

The National Security Commission says via Twitter that Felipe Flores was arrested in Iguala, Guerrero state, on Friday morning.

The students from the teacher's college at Ayotzinapa were taken by police in Iguala on Sept. 26, 2014, and have not been heard from since.

Authorities say they were handed over to a drug gang and killed. But independent experts who reviewed evidence in the case have cast into doubt prosecutors' contention that the students' bodies were incinerated in a massive trash dump fire.

The disappearances and authorities' inability to conclusively clear up what happened to the students have been an embarrassment for the government of President Enrique Pena Nieto.