We are raiding the Guardian Long Read archives to bring you some classic pieces from years past, with new introductions from the authors.

This week, from 2020: When the Colombian army defeated the Farc guerrillas, ending decades of conflict, General Mario Montoya was hailed a national hero. But then it was revealed that thousands of ‘insurgents’ executed by the army were in fact innocent men. By Mariana Palau. Read by Lucy Scott