Mexican President Enrique Pena Nieto vowed to find those responsible for murdering dozens of students in the country's southwest and bring the perpetrators to justice.

Forty-three students disappeared after a protest over job discrimination in Iguala in the Guerrero state on Sept. 26, according to a report from the BBC. A mass grave was discovered near the town over the weekend and authorities believe the mutilated remains found belong to some of the missing students.

The local security force has been linked to area gangs, complicating the investigation. Mexican federal forces have taken control of security in Iguala and have disarmed the city's police force in response to the corruption allegations.

Mexican national security commissioner Monte Alejandro Rubido Garcia said Iguala's police officers will be sent to another city to be evaluated.

"We need to find the truth and make sure the law is applied to those responsible for these outrageous, painful and unacceptable acts," Pena Nieto said in a televised address, Reuters reported.

So far, 28 bodies have been found in the grave near Iguala and Inaky Blanco, attorney general of the Guerrero state, said that it's likely the bodies belong to the students, but added that he's unsure of the motive of the killing.

Blanco said that it could take up to 15 days to confirm the identities of the bodies found in the grave. Two gang hit men have come forward and said they killed 17 of the missing students with the help of Iguala security officials.

Angel Aguirre, governor of Guerrero state, said he's positive the students were killed by gangs working with the local police, adding that he expects some of the bodies found in the mass grave to be students.

"It could well be them. I don't rule it out, it's a very real possibility," Aguirre said. He has received criticism in the past for not putting an end to the violence in the state.

So far, 22 Iguala police officers have been arrested in connection with the violent events that led to the discovery of the grave.