The 13 Colombian social activists arrested in relation to two bomb attacks in Bogota on July 2 deny accusations by authorities including President Juan Manuel Santos of involvement in the incidents and belonging to the National Liberation Army, the country's second largest guerrilla group. The activists also deny having ties to reach other. Social organizations charge the arrests are part of a government strategy to stigmatize protest movements. Natalia Margarita reports from Bogota. teleSUR