An interim governor has been appointed in the Mexican state of Guerrero, where 43 students went missing after clashing with police a month ago.
State lawmakers said Rogelio Ortega, the head of a local university, would temporarily replace Angel Aguirre, who resigned last week over the disappearances.
A manhunt continues for Iguala's mayor, his wife and the city's police chief.
They allegedly ordered the police to hand over the students to gangsters.
They are believed to be on the run.
Eyewitnesses say they saw the students being bundled into police cars.
Last week, the country's Attorney General Jesus Murillo Karam said there appeared to be deep ties across the southern state between politicians, the police and drug gangs.
Rogelio Ortega, the former head of the Autonomous University of Guerrero, will stay in his new post through next year.
He replaced Angel Aguirre who stood down on Thursday to create "a more favourable political climate to bring about the solution to the crisis".
He had faced criticism since the events in Iguala in which six people were also killed during the clashes.
The incident shocked the country and sparked demonstrations across Mexico. One month on, frustration is growing with no word on the fate of the students.
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 recruitment practices, and to collect funds for their college.
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 lorry and took them away.