BOGOTA, Colombia — Colombia's second-largest rebel group on Thursday freed a captive former congressman whose release was a key condition for the start of peace talks with the government.

The National Liberation Army turned Odin Sanchez over to a humanitarian commission including members of the International Committee of the Red Cross.

Sanchez was expected to be welcomed as a hero in his native Quibdo, in western Colombia, for his brave decision last April to swap himself for his ailing brother, who had been taken captive by the ELN a few months earlier.

"I've always been free spiritually," said Sanchez, apparently good health, in televised comments from the jungle hideout where he boarded a helicopter to freedom.

President Juan Manuel Santos has made Sanchez's release a condition for starting long-delayed peace talks with the group known as the ELN. A peace deal with the much larger Revolutionary Armed Forces of Colombia is now being implemented.

"The road to starting the negotiations and having a complete peace is now clear," Santos, winner of last year's Nobel Peace Prize, said at a conference in Bogota with fellow laureates.

The ELN and government have been holding exploratory peace talks for more than three years. Almost a year ago they announced the start of formal negotiations.

But those talks were frozen before getting off the ground after the ELN announced last April it was holding Sanchez, who had agreed to a shocking swap to free his ailing brother, who had been taken captive by the guerrillas a few months earlier.

Last month, the government and ELN hammered out a deal to start peace talks with the rebels committing to free Sanchez in exchange for the government's releasing of two jailed ELN leaders, which took place simultaneously Thursday.

With both sides having apparently fulfilled their commitments, the public phase of the peace process is set to begin next week in Ecuador.

Nobody is expecting a quick deal however.

While much smaller than the FARC, the Cuban-inspired ELN is seen as more ideologically entrenched and has a decentralized decision-making structure that may make it harder to reach consensus among its 1,500 fighters.

Meanwhile the conflict continues to rage. Last week the ELN captured an off-duty soldier, accusing him of spying on the rebel group.