Mexican federal police have detained a former mayor and his wife accused of ordering attacks on teaching college students that left six dead and 43 missing.
Jose Luis Abarca, former mayor of the southern city of Iguala, and his wife, Maria de los Angeles Pineda, were arrested in Mexico City without resisting, according to security officials.
The couple are in the custody of the Attorney General's Office, where they are giving statements. More than a month after the attacks on September 26, Mexican authorities still have not determined the whereabouts of the 43 students.
The rural college students disappeared after an attack by police in Iguala, in the southern state of Guerrero.
Authorities say it was ordered by Abarca, who thought the students were aiming to interrupt a speech by Ms Pineda, and was carried out by police working with the Guerreros Unidos crime gang. Authorities say Ms Pineda was an operative in the cartel.
The search for the students has taken authorities to the hills above Iguala, where 30 bodies have been found in mass graves but have not yet been identified. Last week, the search turned to a gully near a rubbish dump in the neighbouring city of Cocula, but still no remains have been identified.
The fruitless search for the students has sparked increasingly violent demonstrations that included the burning of Iguala's city hall by protesters last month.