Mexico's national human rights commission says it found a witness to the 2014 disappearance of college students who reported that federal and municipal police were present when 15 to 20 youths were taken off a bus and disappeared.

The commission member leading the case, Jose Larrieta Carrasco, said Thursday the evidence suggests two federal police officers allowed local police to take the students.

A total of 43 students from a rural teachers college disappeared in Iguala on Sept. 26, 2014.

Larrieta says the witness overheard conversations by Iguala police who forced the bus to stop by shooting out its tires. When federal police arrived and asked what was happening, an Iguala officer reportedly said they were taking the students away for "the boss" to decide what to do with them.