Karina was sentenced to 33 years for murder and kidnapping
The Colombian government is to release two former leftist guerrillas from prison after they renounced violence and vowed to work for peace.
The interior ministry said the ex-Farc members known as Karina and Olivo Saldana would help other former fighters reintegrate into society.
Correspondents say Karina was one of the most feared Farc leaders before she gave herself up unexpectedly in 2008.
Officials have faced criticism over the failure of a similar plan in the past.
The release of the two ex-guerrillas is the latest stage of a government campaign to encourage desertion from the rebels, a policy that saw 3,000 guerrillas turn themselves in during 2008.
Kidnapping and murder
Karina, whose name is Elda Mosquera - but who also held an identity card under the name Nelly Avila Moreno - was previously found guilty of massacres, murders and kidnappings, and was sentenced to 33 years in prison.
Not that long ago she was the scourge of north-western Colombia, says the BBC's Jeremy McDermott, in Medellin.
Known as a female Rambo in the Farc, her desertion in May last year was a coup for the government, he adds.
Olivo Saldana, the alias of Raul Agudelo, was captured five years ago and convicted on several counts of murder, kidnapping and extortion.
While in jail he led a movement of Farc prisoners who wanted nothing more to do with the rebel army and sought to take advantage of generous government amnesty legislation.
While the two ex-rebels will act as "promoters of peace" for the government, they will certainly not be promoting any dialogue with their former comrades, as they are under sentence of death by the Farc, our correspondent adds.
What the government is really using them for is as examples of what can happen to rebel leaders who collaborate with the authorities and betray the Farc, he says.
At the end of last year another Farc guerrilla, alias Isaza, who deserted with a Farc hostage, was sent to a new life in Paris with his girlfriend.