Relatives of the students have questioned the conclusions of the investigation, urging authorities to keep looking for them despite claims they were killed and incinerated at a landfill by a drug gang in southern Guerrero state.
Mexican authorities have expanded the search for 43 students who vanished after they were abducted by corrupt police in 2014, a government official said.
Relatives of the students have questioned the conclusions of the investigation, urging authorities to keep looking for them despite claims they were killed and incinerated at a landfill by a drug gang in southern Guerrero state.
Roberto Campa, the deputy interior minister for human rights, told AFP that the authorities are looking into allegations that the students were taken to other locations.
Campa said: "The big question is, what did they do with the boys after making them disappear?"
The official said authorities conducted searches in the central states of Mexico and Puebla in recent weeks.
"The effort that has been done in recent weeks have been extraordinary," Campa said.
In total, 600 search operations have taken place since the students disappeared in the city of Iguala in September 2014, Campa said.
"We are working exhaustively on four lines" of investigation, Campa said in Tuesday's interview.
Attorney General Arely Gomez will discuss the new lines of investigation when she meets with parents of the students on today.