Mexican authorities on Tuesday arrested the former mayor of a southern Mexican town accused of ordering police to attack a group of students in September, an incident which led to six deaths and 43 student disappearances. The mayor and his wife had been on the run since the day after the attack.

Former mayor José Luis Abarca and his wife, María de los Ángeles Pineda Villa, were both detained in Mexico City early Tuesday, the local police department confirmed. The federal search for the missing students is ongoing, more than a month after they first disappeared.

Abarca was the mayor of Iguala, a town in the southern state of Guerrero, where the deadly police attack on students occurred on Sept. 26. Authorities believe he ordered the police to crack down on the students, who had been in town to raise funds for an upcoming protest, for fear that they would try to disrupt a speech Pineda was giving nearby that day. Federal officials say that Abarca and Pineda have deep ties to organized crime groups in Iguala.

The case of the 43 missing students has dominated headlines throughout Mexico over the past month, as anger continues to swell over police corruption and insecurity in the country. The episode has spurred mass protests and tested the economy-focused agenda of President Enrique Peña Nieto. University students have called for a nationwide strike on Wednesday to demand that authorities ramp up their search for the students.