Colombia's ELN guerrillas on Thursday freed Odin Sanchez, a politician they held hostage for over ten months. The government released two rebel prisoners in exchange.
Sanchez was handed over to the Red Cross in the remote jungle region of Choco in western Colombia.
He went into ELN custody to take the place of his brother Patrocinio, a former governor who had fallen ill after three years in captivity.
The prisoner exchange comes ahead of talks between government and the ELN expected to begin next week in Equador's capital Quito.
The talks were due to open last October, but broke down after the ELN refused to release Sanchez.
The ELN is the last active rebel group in Colombia.
The government of President Juan Manuel Santos is currently implementing a peace deal agreed last year with the Revolutionary Armed Forces of Colombia (FARC).
Colombia hopes next week's talks with the ELN will seal a "complete peace" to end the country's 52-year conflict which has killed more than 260,000 people.