Missing Mexico students: Guerrero state governor to resign
The governor of Mexico's southern Guerrero state - where 43 students went missing after clashing with police last month - has said he is standing down.
Angel Aguirre said he hoped the move would create "a more favourable political climate to bring about the solution to the crisis".
He has faced growing criticism since the disappearance of the students in the town of Iguala on 26 September.
Eyewitnesses described seeing them being bundled into police cars.
Six people were killed during the clashes.
Mexico's Attorney General Jesus Murillo Karam on Thursday said there appeared to be deep ties across the southern state between politicians, the police and drug gangs.
He said arrest warrants had been issued for Iguala Mayor Jose Luis Abarca, his wife, and the town's police chief. They are suspected of ordering the police to hand over the students to local gangsters.
All three suspects have gone missing.
On 26 September, a group of students from a teacher training college in Ayotzinapa travelled to nearby Iguala to protest against what they said were discriminatory hiring practices, and to collect funds for their college.
The college has a history of left-wing activism and according to Mr Murillo Karam, Mayor Abarca had been angered by a previous protest they had held in the town.
On the same day, the mayor's wife was holding an event in the town.
Local media have long speculated that the ensuing police crackdown on the students may have been related to her public appearance.
Mr Murillo Karam said police officers had been told to prevent the students from disrupting his wife's event.
Police opened fire on the buses the students were travelling in, killing three of them and three more people in nearby vehicles.
One busload of students tried to flee but was stopped by the police and taken to Iguala police station.
The prosecutor said gang members then loaded them onto a pick-up truck and took them to Pueblo Viejo, where a number of mass graves have been found.
Forensic tests suggested 28 bodies found there were not those of the students, but Mr Murillo Karam said they "may have been flawed".
Mr Murillo Karam said two more bodies had been discovered since.
A total of 52 people, including police officers, local officials and gang members have been arrested in the case.