Ciro Bustos was on trial for guerrilla activities in Bolivia when he heard that Che Guevara had been killed. “When I heard…it felt as if a bullet had hit me,” he says.

As the news of the Cuban revolutionary leader’s death ricocheted around the world, Bustos, a fellow Argentinian, had more reason than most to feel his life had been knocked off course. In the months leading up to Guevara’s execution on 9 October 1967 he had been one of his most trusted collaborators.

Guevara was planning for Bustos to lead the next stage in his master plan. In his “Second Declaration of Havana” in 1962, Guevara famously called for socialist revolution throughout Latin America, and Bustos had come to meet him to put the finishing touches to their strategy to spark an uprising in Argentina. But history – and the CIA – had other plans.

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On 19 April 1967, Bustos said goodbye to Guevara. “I could see that if we didn’t leave at that moment we would be stuck in the jungle,” says Bustos. “The Bolivian army was turning the whole area into a military zone.”

With Bustos was the French intellectual Régis Debray, another disciple of the Guevara cause. Before they left, Guevara presented Bustos with his imitation sheepskin jacket to keep him warm. “If you’re arrested the most important thing is to conceal the presence of the Cubans here and my presence, too, for the time being,” Guevara told him. “But, if you see they know everything, go for it, try and make as much noise as possible.”

His warning proved fateful. Bustos and Debray were arrested close to Muyupampa by the Bolivian army on 20 April. When Bolivian officers interrogated him, Bustos, obeying the first part of Guevara’s instructions, pretended he was Carlos Alberto Frutos, an amateur journalist covering the rights of political prisoners. His cover held, even when his interrogators were joined by the chief CIA operator in the Bolivian field, Dr Eduardo Gonzalez.

Rumours of Guevara’s presence in the jungle had circulated for weeks and the CIA were certain they could get definitive proof from the two prisoners. It was only after 20 days, when Bustos’s true identity was revealed by his fingerprints, that he agreed to draw some rough sketches of the guerrillas in the jungle, and a map of where the camp was. By this point, he says he could see his interrogators already had the information they were looking for. Yet on the basis of these sketches Bustos has been framed by some – most notably Che’s French biographer, Pierre Kalfon – as Guevara’s traitor.

Now, just over four and a half decades later, Bustos has written a vivid account of his side of the story – Che Wants To See You.

Today Bustos lives on his own in Sweden. Even at 81, he still displays the wiry physique and granite determination that helped him to survive the rigours of life as a guerrilla. He remains frustrated at the lurking conspiracy theories about his role in Guevara’s final days.

He describes how one of his first encounters with Guevara was in 1961 at the Habana Libre hotel that had been commandeered by Castro as his headquarters. “Everything that happened in Cuba was happening at the Habana Libre then,” he laughs. “I heard that Che was going to be playing chess there.”

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The occasion was a championship in which the Polish chess legend Miguel Najdorf, took on 40 different players. He was blindfolded while his opponents played without restrictions. In his book, Bustos recalls: “The match ended with the hopes of most challengers dashed, Che’s included. In this particular battle, the strategist in chief was Najdorf.”

Yet it was Guevara’s grand strategies that would soon provoke world attention. In 1961 he was looking for individuals he could trust to put his theory of the “foco” into practice. This was the idea that a small nucleus of fighters can overcome a regular army in a country plagued by inequality, because the oppressed people will rise up and strengthen a determined struggle for power.

In July 1962, his close friend Dr Alberto Granado told him he should think about recruiting Bustos, who was then giving lectures on art appreciation in Santiago. Bustos, an Argentinian artist, had championed the Cuban revolution ever since hearing a journalist’s radio interview in 1958 with Guevara and Castro as they camped out in Cuba’s Sierra Maestra.

“It was immediately clear it was very important – I told everyone I knew about it,” he says. Right from the start he related more strongly to Guevara than the revolution’s leader. “[His] voice spoke to me personally, from conscience to conscience,” says Bustos.

He made the precarious journey from Argentina to Cuba in 1961. When Che recruited him the next year, it was decided he would join what eventually proved to be a failed venture led by Jorge Masetti – the same journalist who had inspired him to go to Cuba – to foment guerrilla warfare in Argentina.

Bustos was one of the few involved to emerge from that first Argentinian expedition with any credit. Guevara summoned him back to Havana to ask him to return to Argentina to co-ordinate a national guerrilla front. “He made a somewhat jokey reference to the fact that I was still alive,” Bustos says. After that meeting they would not see each other for almost three years.

Bustos’s account of their final Bolivian venture contrasts his excitement about seeing Guevara. “It was as if the chief electrician had suddenly illuminated the stage,” he says, against the fighters’ growing awareness of the odds being stacked against them. They knew the Bolivian communist leadership was against the operation.

On the world stage, Russia was becoming increasingly edgy. And multiple desertions from Guevara’s troops led directly to the Bolivian army’s discovery not just of the original camp but of photos of Che and other of his soldiers in the jungle.

The operation was doomed almost before it started. But for those who want to pin the blame for Guevara’s discovery on the evidence unearthed by the CIA during their interrogations, the question has been which of the two prisoners – Debray or Bustos – cracked first?

Both Jon Lee Anderson, Guevara’s biographer, and the Swedish documentary Sacrificio, made in 2001, argue that because Bustos concealed his identity for 20 days, it was Régis Debray who gave the CIA what they were looking for first.

Both men were in an impossible position. Yet Debray emerged as a hero and Bustos, after being convicted for guerilla activities in Bolivia after standing trial in 1967, was consigned to obscurity under a shadow. Mr Debray did not respond for a request for comment by The Independent.

Looking back now, was Bustos aware as he drew those pictures that day, that they would change the course of his life? “I have been asked this question so many times,” he sighs. “It meant nothing. All I did was draw people with beards.”

Death in Bolivia: Guevara’s last days

4 November, 1966: Disguised as a middle-aged Uruguyan businessman, Guevara travels to Bolivia to launch a revolution.

April-September, 1967: Che’s group wins several battles but struggles against CIA-backed Bolivian forces.

7 October: Informant reveals location of Guevara’s guerrilla camp. Bolivian troops encircle the position. Guevara is wounded and taken prisoner.

9 October: President René Barrientos orders that Guevara be killed despite pressure from the US to extradite him. Guevara is shot nine times with a semi-automatic rifle to give the appearance that he was killed in battle.