A report by an outside group of experts says there is evidence that Mexican police tortured some of the key suspects arrested in the disappearance of 43 students.

The group said Sunday that a study of 17 of the approximately 110 suspects arrested in the case showed signs of beatings.

One suspect said he was nearly asphyxiated and another had been slapped on the ears so hard his eardrums broke.

The Mexican government recently released documents suggesting investigations had been opened against police and military personnel, but has refused to say if any have been arrested or charged.

The 43 students have not been heard from since they were taken by local police in September 2014 in the city of Iguala, Guerrero state.