Dusk was falling as the apparently ordinary middle-aged man parked his car opposite the towering white statue of an angel in the Andean mountain city of San Cristobal near Venezuela's border with Colombia.
Daniel Barrera walked the few feet to a bank of public payphones facing the church, picked up the handset and dialled a number. But he had barely begun his conversation when, to the shock of shopkeepers and passers-by, dozens of armed police appeared - and the 20-year career of the last of the notorious Colombian drug barons was over.
Known simply as "el Loco" - "the crazy one" - for his for violent mood swings and ruthless dispatch of rivals, Barrera was captured by Venezuelan security officers without a fight last week as he telephoned a subordinate to issue instructions.
"He just shrugged and had the look of a resigned man who knew his time was up," a street vendor who witnessed the arrest told The Sunday Telegraph. "The National Guard pulled up on motorbikes and he surrendered without a struggle. It was over in no time."
The Venezuelan swoop was conducted after a months-long monitoring operation co-ordinated by Colombia with Britain's MI6 and American intelligence -- an indication of the depth of concerns about Barrera's kingpin status trafficking cocaine to the US and Europe.
British officials were predictably discreet about their involvement, but senior Colombian figures revealed that the UK had played a crucial role. This is believed to include training the Colombian services and providing assistance with electronic eavesdropping as Barrera flew around the region.
Indeed, so central was the British role that Jose Roberto Leon Riano, Colombia's police chief, flew to London just days before the raid to discuss the final details of the operation.
And Juan Carlos Pinzon, the country's defence minister, disclosed for the first time in a television interview that Colombian intelligence has been working closely with MI6, as well as their long-time US allies, for several years and that this was not the first drug arrest made with such collaboration.
Barrera is believed to have been operating his international narco-empire from San Cristobal for the last four years, living under aliases and moving between nondescript apartments and guest-houses in the border city.
He had gone to striking physical lengths to hide his identity and, it has now emerged, satisfy his vanity. Most notably and painfully, he had burned his hands with acid to erase his own fingerprints.
He had also undergone cosmetic surgery to his face and extensive liposuction to his stomach. The only known picture of Barrera before his arrest shows a portly figure and the drug-lord admitted to a female Colombian operative who infiltrated his entourage that he was obsessed with looking thin.
If his goal in San Cristobal was anonymity, then he was, for a long time, successful. He spent his last three months at large at the Remanso guest house where rooms in the Spanish colonial-style building in an upper-middle class neighbourhood cost $50 to $100 a night.
The first indication for staff that the quiet polite guest who spent much of his time in his room was South America's most wanted man was when Venezuelan police arrived to search the premises shortly after his arrest.
"He was very gracious and kept to himself," said an employee. "He was a generous tipper and did not want to be bothered. We had noticed the marks on his hands, but never imagined he had deliberately burned himself."
Barrero was also a regular visitor to a two-bedroom apartment in an unprepossessing block above a chemist's shop and small restaurant. The property was rented by an occasional girlfriend of the drug baron, but neighbours recalled him last week only for how unremarkable he was.
In San Cristobal, he explained his regular trips out of the city by saying that he owned cattle ranches in three states near the Colombian border. Those ranches may in fact be part of what authorities now believe are some 500 businesses that he established to launder the profits of his real business.
But Barrera was also travelling much further afield, making regular trips to Argentina and Brazil to see children fathered by other relationships. And earlier this year, he flew to west Africa to oversee arrangements for his cartel's shipments of cocaine via there from Venezuela to Britain and western Europe.
He had steadily risen up the ladder of Colombian narco-traffickers during the 1980s and 1990s as rivals were captured or killed. At the same time, he demonstrated his skills for drug-dealing diplomacy as he built good links with both the Marxist FARC rebels and right-wing paramilitaries that finance their operations by growing and smuggling cocaine.
But like many Colombian drug bosses in recent years, Barrera moved to the safer haven of Venezuela as his homeland, helped by the US, pursued an increasingly tough and successful anti-narcotics programme.
He was not the first drug lord to seek refuge in San Cristobal, a sprawling city of pastel-coloured homes running through the folds of the Andes conveniently near the border.
It is a good place to disappear. And in an earlier unwanted claim to notoriety, it was also the birthplace of the Ilich Ramirez Sanchez, the left-wing terrorist better known as Carlos the Jackal.
The Sunday Telegraph has now pieced together details of the complex and lengthy multi-national operation that led to Barrera's downfall. The first breakthrough for the Colombian authorities came with a computer seized when FARC commander Víctor Julio Suárez Rojas was killed two years ago.
The files revealed crucial details about Barrera's links to the group, including the name and role of his sister's son. That unnamed nephew was persuaded to co-operate with the Colombians and now stands to share in the $5 million American bounty on Barrera's head and is expected to be moved to the US with a new identity.
He disclosed that his uncle only trusted his closest relatives and a small-knit circle of aides who served as drivers and assistants, including several women, for whom the paunchy lothario had a marked weakness.
The turncoat nephew provided vital information. But fearing that he might stop co-operating, and in what could be a script for a Hollywood thriller, the Colombians managed to insert a "honey-trap" female into Barrera's entourage.
She too supplied crucial details about his modus operandi, including the fact that he did not use a bodyguard to remain low-profile and relied on public telephones to run his empire so that landlines and mobiles could not be traced. And he also confided to her his obsession with becoming thin.
As Bogota monitored his movements with American and British assistance, they picked up "chatter" earlier this year that he had flown to west Africa. That trip highlighted British concerns about the increasing flow of cocaine via "phantom" flights from Venezuela to countries such as Nigeria and then on to Europe, with much of it destined for the UK.
Barrera returned to Venezuela in May amid signals from aides that he was willing to consider surrendering himself to the US authorities on certain conditions, believed to include favourable treatment for relatives. It is unclear whether that out-reach was ever genuine, but the planned negotiations stalled and Barrera disappeared again on journeys within South America.
But on August 6, the Colombians picked up his trail again. Sharing the information with their historic foes the Venezuelans, as well as working with the Americans and British, an unprecedented surveillance operation was mounted for the next 45 days.
Tarek El Aissami, the Venezuelan interior minister, said that his country deployed 14 intelligence teams across 4 states and tapped 69 public phones - including the one opposite The Church of the Angel where Barrera was tracked down early on Tuesday evening.
Even as the merciless Mexican drug cartels spread their tentacles of terror to take over trafficking operations from South America, his capture was hailed as a major breakthough.
Indeed, in the international anti-narcotics world, Barrera was regarded as the second most important and wanted drug trafficker on the planet after Mexico's Joaquin "El Chapo" Guzman, head of the feared Sinaloa cartel.
Barrera is in custody in the Venezuelan capital Caracas this weekend. He is expected to be deported to Colombia, from where the US is already seeking his extradition to face trafficking and money laundering charges
Venezuelan authorities moved last week to close down his operation, arresting four associates following his capture -- including Marta Lucia Franco Aguilar, 38, his long-time girlfriend and business manager, known by the alias "Rocio".
"'Rocio' is his trusted woman, who has accompanied him since he left for Venezuela in 2008," said Gen Leon Riano, the Colombian police chief. "She manages all his affairs, principally those related to the control of fronts, the control of international connections and those who control the international cocaine shipments."
In Caracas, Mr El Aissami described the arrest as "the biggest blow that we have given to organized drug trafficking criminals here in Venezuela in history."
Announcing the arrest on Tuesday, Juan Manuel Santos, the Colombian president, hailed the fall of "the last of the great capos".
But his predecessor Alvaro Uribe suggested that Venezuela had arrested Barrera to burnish President Hugo Chavez's anti-crime credentials ahead of October 7 presidential elections.
"Chavez has turned Venezuela into a paradise for drug trafficking and he has to save face," he commented.
In London, Government sources refused to be drawn on the role of UK intelligence in the arrest. But they noted there was "extensive and long standing co-operation" between Britain and South American countries to "stem the tide of drugs" exported from that part of the world.
In that battle, they have just achieved one of their greatest overseas successes. For "el Loco" Barrero, life is crazy no more.
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British Intelligence helped track down Columbian drug lord Daniel 'el Loco' Barrera