Born in 1961 to a former Colombian education minister and an ex-beauty queen who campaigned for the destitute, Ingrid Betancourt was raised in both Bogota and in Paris, where her father was sent as an ambassador to the cultural agency Unesco. He often told her and her elder sister Astrid: “You have received a great deal from life, you are privileged children. So you have a duty to give back what you received and serve your country.”

While an 18-year-old student at the Institut d’Etudes Politiques in Paris, she fell in love with Fabrice Delloye, a French diplomat 10 years her senior. They married and hopped from posting to posting.

It was only in 1989 that she decided to follow her father’s advice and serve her country. “I had the impression I was wasting my life, that I was doing nothing,” Betancourt says. “I decided that life had a meaning only if you serve others so I went back to Colombia.”

The trigger was the assassination of a Colombian presidential candidate, Luis Carlos Galan. He was as close as Colombia has got to its own Barack Obama, an inspirational figure who seemed to offer hope to a country benighted by violence, corruption, poverty and the drugs trade.

Colombia is notorious internationally as the source of much of the world’s cocaine and as the homeland of the ruthless criminal cartels that export the drug. Its political problems arose long before the “narcotraficantes” came onto the scene, however. It has a decades-old history of 20th century political warfare, known as La Violencia.

In an attempt to stem the bloodshed, its rival political parties alternated power through pro forma elections. But this cosy deal alienated voters and fed corruption. Many young idealists took up revolutionary politics; some wealthy, well-educated Colombians turned hopelessly to drugs and hedonism.

Galan mobilised the disillusioned generations by aspiring to turn the nominal democracy into a genuine one, but the powerful interests he challenged did not hesitate to kill him. Betancourt says: “Galan’s death accelerated things for me but I think I’d have gone back anyway. I had to go back.”

She separated from her husband, whom she later divorced, and entered Colombian politics. Fighting corruption was her priority. “I find it unacceptable that the limited resources of a poor country are deviated into the bank accounts of dishonest people. I don’t like it and if I can do something about it I have to do it. But I didn’t realise what a snake pit I was getting into. I found myself in an awful world of dirty money and drugs and crime and so I made a series of monumental blunders.”

Creating her own small political party, Oxygen Green, she “just piled up enemies by the bucket-load, a hundred a minute. And I had very few friends”.

One of the key elements in the Colombian political equation was – and still is – Farc, the Revolutionary Armed Forces of Colombia. The group was founded in 1966 with roots in impoverished rural areas. Since then it has accumulated untold wealth through cocaine trafficking. Farc also owes its strength to unrivalled mobility and knowledge of the terrain, moving in groups of 10 to 15 through mountain passes and sun-drenched valleys. Rebels sleep in hammocks with their boots on, ready to move. There is no precise estimate of how big Farc is; the army put the number at 18,000 in 2002. About a third are believed to be women.

“The guerrilla is, above all, a way of life. For a peasant’s son, condemned to a miserable life in the fields, a gun is a symbol of moving up the social ladder,” said Alfredo Manrique, a petroleum engineer who was kidnapped for a year and a half.

Betancourt thought she could take on the Farc guerrillas by political rhetoric. She went on television to challenge them: “What happened to your ideals? Is it to sell cocaine that you decided to take up arms?”

Critics called her a bourgeois Joan of Arc. Elected an MP and then a senator, she received death threats – one read: “Leave, we have already paid the killers” – and was given a 12-man bodyguard. When she received a photograph of a child that had been cut up into small pieces, she sent her own children, Melanie and Lorenzo, to stay with their father in New Zealand, his latest posting. But she did not give up politics.

“You don’t ever give up. But I wasn’t going to put my children at risk so I had to get them out immediately. And there was something else about the threats I received against me: I thought they were to scare me, I always thought nothing would happen to me. I was naive. I thought I was, in a way, untouchable.”

In 2002 she stood as a candidate in the presidential election. On the campaign trail in February that year, she was determined to reach the southern town of San Vicente del Caguan, a former Farc bastion that the army was about to reconquer. She set out by road despite having no escort. Two guerrillas manning a roadblock told her to turn back. She refused and told them: “I want to see your chief.”

A few minutes later she was led away into captivity to join the many hostages Farc was holding as pawns in peace negotiations with the government. She became their most valuable pawn of all.

Betancourt thought “for years and all the year long” about her decision to set out for San Vicente del Caguan that day. “Each time, thinking those moments through second by second was torture. I told myself I shouldn’t have done it but in the end I decided that I had to do it. I had no choice. I didn’t know the danger and, given what I knew, I had to go. It was a question of principle for me.”

During her captivity, Farc’s fortunes have changed a good deal. Frustrated by a long and sterile peace process, three months after Betancourt’s kidnapping, voters elected a rival candidate, Alvaro Uribe, as president. An austere and pious lawyer, whose father was murdered by the rebels, he had run for office on the slogan “iron fist and big heart” and pledged to vanquish Farc. Since then, his government claims to have secured key roads and reduced the number of murders and kidnappings. The rebels’ military power has been weakened by government forces deploying Black Hawk helicopters and fighter planes supplied by the United States. The army says Farc’s numbers have fallen to 10,000, and an estimated 3,000 are reported to have given themselves up over the past year.

Uribe’s line has won him widespread praise at home; he was triumphantly reelected two years ago and surveys show he is popular with 80% of voters. But both the Betancourt family and Nicolas Sarkozy, the French president, came to fear that Uribe would unleash a military raid that would cause the deaths of hostages.

Sarkozy saw red in March when, in the middle of negotiations by French envoys involving the leftist Venezuelan president Hugo Chavez, whose sympathy for the Farc’s ideology is well known, Uribe ordered the bombing of a rebel camp in Ecuador. Raul Reyes, Farc’s deputy leader, died in the attack.

Exploiting Chavez’s support, Farc has been pushing for a “humanitarian exchange” – 50 hostages for 500 jailed rebels. The Colombian government hopes that the rescue of Betancourt, Farc’s most valuable hostage, will make it adopt a new approach in negotiations.

“What we hope is that the Farc will at last see reason. If they don’t negotiate for peace in good faith now, tomorrow there won’t be anything to talk about,” Juan Manuel Santos, the defence minister, said last week. “If they want to negotiate, we’re ready. Otherwise the military pressure will become stronger.”

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