Partly it was the midnight bicycle rides the man took around the nearby lake, wearing sunglasses and a thick woolly hat. Partly it was his insatiable penchant for takeaway food, his apparent reluctance to leave his house and the fact that he never answered his telephone. Mostly, however, Mr Amaral was suspicious of the constantly changing appearance of the 44-year-old expat.

"It wasn't just me. All of the guards thought he was kind of mafioso," he said. "He used all these different hats. He changed his hair all the time; first it was black, then blond and then white. He had sideburns, then a moustache, and he wore dark glasses. All of the windows of his cars were blacked out."

What Mr Amaral did not realise was that the reclusive resident was Juan Carlos Ramírez-Abadía - a 44-year-old drug kingpin described this week as one of the world's most wanted narco-traffickers. Abadía, who was seized at his Morada dos Lagos hideout on Tuesday by Brazilian federal police and was better known as Chupeta, or Lollipop, is accused of ordering more than 300 murders and smuggling billions of dollars worth of cocaine into the United States and Europe.

South American newspapers have described Abadía, who is charged with leading the Norte del Valle, Colombia's largest cocaine cartel, as the heir to Pablo Escobar. One key business partner, it emerged this week, was Juan Carlos Ortiz Escobar, the nephew of the infamous Medellín drug boss.

Fortress

Nestled in the eucalyptus-covered hilltops outside Sao Paulo, the fortress-like Morada dos Lagos condominium is the perfect place for somebody seeking privacy. The leafy, gated community is hemmed in by a towering, 3,500-volt electric fence and is policed day and night by a private security force armed with revolvers and machetes.

A large sign, near the estate's entrance, promises everything a rich Brazilian businessman, or indeed a fugitive drug trafficker, could dream of: "Security, tranquillity and harmony."

It was here, about two years ago, that Abadía began to build his Brazilian HQ, administering his global cocaine empire from a luxury mansion, equipped with a gym and swimming pool.

Last Tuesday his fiefdom began to crumble as dozens of federal police swept into the mansion and arrested the Colombian. He was dressed, according to witnesses, in just his underpants.

Abadía's life as a cocaine capo reportedly began in 1986. A university-educated horse enthusiast from the city of Palmira in south-west Colombia, he joined the Cali cartel in the mid-1990s at a time when it dominated the Colombian cocaine market following the 1993 killing of Pablo Escobar.

After a 1995 crackdown on the Cali cartel, Colombian authorities say he switched to the Norte del Valle cartel, becoming one of its leaders. In 1996 he was sentenced to 13 years in prison in Colombia but by 2001 he was free again.

Keen never to return to jail, Abadía plotted his escape to Brazil. According to a statement given to Brazilian police this week, he boarded a small boat bound for Brazil's north-eastern coast in 2004, carrying $4m (£2m) in cash. From the north-eastern state of Ceara he travelled in a small aircraft to Barretos, a town in the interior of Sao Paulo state. Soon after this he set up camp in the Morada dos Lagos, one of five secluded condominiums in Aldeia da Serra, 20 miles from the centre of Sao Paulo.

Police claim Abadía commanded a sprawling network of businesses from here - among them a jet ski outlet, cattle ranches and hotels - which were used to launder the profits from cocaine sales in the US and Europe. Some estimates this week suggested the trafficker was worth as much as $1.8bn. He also purchased farms and luxury homes across Brazil.

The £500,000 Sao Paulo mansion, which the Guardian visited this week, was packed with designer furniture, top-of-the-range electronic equipment and nearly $1m in cash. He shared the house with his Colombian wife, and two miniature pinscher designer dogs, one of which was keeping a lonely watch from the master bedroom this week as federal police scoured the house for fake walls and hidden evidence.

Abadía kept the lowest possible profile at Morada dos Lagos. The estate's 39-year-old manager, Marco Antonio de Souza, said he rarely left his house and had no guests. Instead the Colombian preferred to order takeaways from the local bakery, La Ville, and watch DVDs on his 1.8-metre (72 inch) plasma screen TV. He never answered the telephone, the condominium's receptionist said.

"He never said anything to us," said Mr Amaral. "He'd just raise his hand and make gestures."

Occasionally, it seems, he did leave his lair, not least to undergo several major sessions of plastic surgery at a well-known clinic in Sao Paulo's chic Jardins neighbourhood. Mugshots released by the federal police this week showed wounds on Abadía's face - proof, they said, that he had undergone a recent operation, possibly his sixth.

The trafficker also used a series of false passports and names. At the time of his arrest he was posing as an Italian citizen and using a passport issued in Argentina.

He also possessed nearly 150 mobile phones, using each one only once so as not to be traced.

But despite his constant attempts to lie low, Brazilian authorities were gradually closing in on the trafficker for whom the US government was offering a $5m bounty. His downfall reportedly began in 2005, triggered by a minor plane accident in the southern city of Curitiba involving a pilot who was helping smuggle money into the country for Abadía.

According to the Brazilian media, police became suspicious about the amount of money found on the light aircraft, which was being used by the pilot, Andre Luiz Telles Barcellos. Two years of secretive investigation, which eventually led to Abadía, followed.

His fate was apparently sealed when Brazilian authorities sent a sample of the Colombian's voice picked up by a phone tap to the US drug enforcement administration (DEA). Using voice-recognition technology, US agents were able to confirm that the suspect, whose appearance had been radically altered by surgery, was their target. Then, at dawn on Tuesday, the hunt for the Americas' most wanted trafficker came to an end. It was just after 2am when seven black cars belonging to the federal police pulled up at the Morada dos Lagos guardhouse. Minutes later the officers, with two agents from the DEA, were pouring up the trafficker's lawn and past his illuminated, miniature palm trees. The officers forced open the building's thick, triple-bolted front door and pushed their way inside. They first stumbled across the trafficker's naked wife, according to one security guard who was present.

Extradition

Mr Barcellos, the pilot, was also arrested in Tuesday's operation, and stands accused of helping the Colombian smuggle millions in cash into Brazil.

Abadía's arrest came in stark contrast to his cinematic life as a drug trafficker. According to Mr Amaral, who accompanied the police operation at the house, the Colombian offered no resistance and spent much of the day sat on his bed, handcuffed and wearing only his underwear.

"I'll have my whole life to talk to you when I'm there [in the US]," he told the DEA agents, according to reports in one Brazilian newspaper, referring to his possible extradition to the US.

This week, as federal agents continued to quiz the Colombian in central Sao Paulo and US authorities began the extradition process, the manager of the Morada dos Lagos was keen to point out that there was still no evidence that any crime had been committed at the millionaires' estate.

He pointed to the condominium's electric fence which, he said, was capable of throwing off any unwelcome visitors at least three metres. "There's never been a single crime here," Mr Souza insisted, as a second federal police vehicle pulled up outside the Colombian drug baron's home to continue the search.

Meanwhile, there were reports in Brazil yesterday that security had been stepped up at the federal police's HQ in Sao Paulo, due to fears that allies of the reputed drug lord could attempt to rescue him.

Hideout of choice

Brazil has long been considered a popular hideout for those fleeing the long arm of the law, including Nazi war criminals, cocaine traffickers and political fugitives.

Reports in the Brazilian press this week suggest several other major Colombian traffickers may be at large in the South American country. Analysts say Brazil's popularity among traffickers is down to the relative ease with which money can be laundered there, as well as the availability of chemicals used to transform coca leaves into cocaine.

Brazil's most famous expat fugitive was Ronnie Biggs, one of the Great Train Robbers, who spent nearly 30 years in self-imposed exile in Rio. The Italian mafia has also used Brazil as a refuge. According to the Rio newspaper O Globo, some 100 members of the mafia were extradited from Rio to Italy from 1994 to 2004.