The US has been offering $20m for any information leading to Rafael Caro Quintero’s capture.
Mexican drugs lord Rafael Caro Quintero, who is on the US most wanted list, has been arrested in the northern state of Chihuahua, reports say.
Mr Quintero, who is accused of murdering a US drug enforcement agent in 1985, was held in the city of Guachochi, local media say.
The US had offered $20m (£17m) for any information leading to his capture.
In 2013, a court in Mexico freed Mr Quintero after he had served 28 years for the murder of Enrique Camarena.
The court cut short Mr Quintero’s 40-year sentence, ruling that he should have been tried in a state rather than a federal court.
The murder strained US-Mexico ties at the time and changed the war on drugs trafficking.
Mr Quintero was one of three founding members of the powerful Guadalajara Cartel.