At 8.30 a.m. on a January morning, a bespectacled FIFA official is rushing to deliver a presentation close to the site of a new museum the football governing body is building near its headquarters in Zurich. The nine-storey tower, still a construction site clad in tarpaulin and iron scaffolding, is being prepped to become a showpiece of football memorabilia. Above it would be an apartment block, topped by swanky penthouses that would be marketed for rent for the equivalent of $8,000 per month. Around the official, commuters hop on and off trams that pass the sweeping granite façade of Bahnhof Enge railway station. Wearing a grey suit and carrying a briefcase, this Australian who heads FIFA's transfer monitoring agency has come to brief journalists about the latest player trading data in the international transfer market.

Mark Goddard had arrived in Switzerland in 2001 to work for FIFA on routine clerical tasks like hotel reservations, accreditation and ticketing. When his contract expired six years later, he was ready to pack his bags and return home. But then the world ruling body offered him the job of setting up a new online system that would log tens of thousands of international player transfers each year. It would be a clearinghouse for one of the most globalized employment markets in the world: few workers moved to the four corners of the world like footballers. Over the previous five years, South American players had been transferred to 122 of the 195 nations in the world.

The new electronic system was, Goddard said, a chance to improve the regulation of a marketplace in which massive quantities of cash flowed with little or no supervision. “Football is the last area of the commercial world where large amounts of money can be moved without oversight or regulation,” Goddard had told a small group of reporters a few years earlier in an underground, soundproof room at FIFA's headquarters that was usually reserved for the meetings of senior executives. “It's been a jungle out there and that's about to change.”

Goddard and his small team had jetted to 94 countries over the previous two years teaching clubs how to use FIFA's so-called Transfer Matching System, which was a slightly more complex version of a credit card transaction on Amazon.com. After abandoning the laborious process of sending faxes, the system allowed clubs to process a player move to another country in less than 10 minutes if the data submitted by the buying and selling team matched.

It was a new world for many in football. On his travels, Goddard said he had asked a team executive how he usually paid player transfer fees. The official pointed to a steel briefcase, intimating it was to carry bundles of cash. “I told him to tell his chairman that he wouldn't be able to do that anymore,” Goddard said. With the new electronic system, clubs would have to log bank details of the money flow between clubs and agents. They would also have to upload a copy of the contracts.

As he arrived by tram for the 9 a.m. media briefing in a wood-beamed room next to the building site of the museum, Goddard ordered coffee and marvelled at the slickness of Zurich's public transport system. Most commuters in the Swiss city seemed to leave their car at home and as a result there were hardly any traffic jams. He was striving to make football transfers as efficient: over the previous few years, FIFA had acted like traffic cops by handing out more than a thousand fines of up to $15,000 to clubs for infractions such as not filing the correct paperwork.

Based in small rented offices down the hill from FIFA's headquarters, Goddard managed a close-knit group of staff including legal director Kimberly Morris, a bubbly red-haired Canadian, and a collection of computer programmers and administrative staff. He said he also had a network of legal experts around the world to help him with compliance, although he would not give more details. Like Goddard, Morris was new to the intricacies of the football transfer market. She had worked as a commercial lawyer in London for Finers Stephens Innocent before joining FIFA in 2012. She too was enthusiastic to knock player trading into shape but, although they had a generous budget, their influence was limited to a certain extent. They could ask FIFA's disciplinary department to open cases but after that, they remained powerless.

Among the trades in their sights were the transfers through Uruguay that Juan Figer had pioneered in the 1980s. Goddard had visited Uruguay twice to warn clubs that the deals were no longer allowed. After his first visit, he was largely ignored. Kimberly Morris had more success in Zurich: she explained how the operations worked in a written explanation to FIFA's disciplinary committee. In a breakthrough, the committee agreed to take the unprecedented move of sanctioning one of the Uruguayan clubs, Atlética Sud América.

Sud América had registered six Argentine players for a few days without them appearing in a match. The players had been traded there by Argentine teams – Instituto Atlético Central Cordoba, Independiente, Rosario Central and Racing Club – for what FIFA called non-sporting reasons. FIFA's disciplinary committee banned the Uruguayan club from the transfer market for a year, and the Argentine clubs were fined between 15,000 and 50,000 Swiss francs. While the sanctions were small change in an industry where multi-million trades were commonplace, at least they showed FIFA was finally taking action.

But then Goddard suffered a reverse. Football's top tribunal, the Court of Arbitration for Sport, meeting in an 18th-century stately home Château de Béthusy outside the Swiss city of Lausanne, convened to consider an appeal by one of the three Argentine teams, Racing Club. The court appointed a panel of three lawyers to rule on the case: a long-haired Dane called Lars Hilliger, a Buenos Aires-born Israeli named Efraim Barak and Costa Rican football administrator Margarita Echeverria. Together, after considering the evidence presented by football's world ruling body they delivered a hammer blow verdict: “Nullum crimen sine lege.”

Or, in other words, FIFA did not have an appropriate law to render illegal what some called “bridge” transfers. The judgement confirmed that there was a loophole in it's rules allowing a player to be registered with three clubs in a single season and only play for two of them. “The behavior that FIFA apparently nowadays consider to be a violation of its rules has been followed for years by several clubs all over the world, and FIFA has never manifested against it before,” the panel said in a written ruling.

More than a decade earlier, in 2002, the Swiss court had made a similar statement to the one it was now issuing. Back then it overruled a FIFA committee which found that Argentina's Velez Sarsfield had acted “against the spirit and terms” of the regulations by only transferring 50% of a player's economic rights to Espanyol of Spain. “As long as FIFA rules do not issue an express prohibition, clubs are allowed to treat economic rights of players as assets and trade portions of them,” the court said.

To stop such transfers, the 2015 panel advised FIFA to introduce a new law. There is, their written ruling said, nothing in the rules to stop transfers “with a purely economic purpose”. The three arbitrators said that football's governing body should prepare a set of rules which, “in a clear and transparent manner”, prohibit this type of player trading.

What Goddard could not do publicly was blame FIFA's South American executives who had not paid close attention to player transfers since the 1980s. The executives would meet in Zurich on FIFA business five times a year, staying in the five-star Baur au Lac hotel while picking up an annual stipend that had risen to as much as $300,000. They were among the men at the apex of the sport. They were chauffeured around town in black Mercedes-Benz limousines and made the key decisions like where the World Cup would be staged. Goddard, who went to work on public transport, was not in a position to criticize them.

Putting on a positive spin at the media briefing, Goddard said that the new online system had “turned the lights on” in the transfer market. FIFA's head of communications, Walter de Gregorio, joined Goddard for his presentation to ensure the Aussie with his dry sense of humour did not go off message when talking to the assembly of 25 journalists. Gregorio, a tall man who liked to wear aviator-style sunglasses, joshed with the reporters about making it in time a few hours after seeing them at the bar following the ritzy world player of the year awards won by Cristiano Ronaldo. Half an hour into Goddard's speech, the Ferrari-driving Swiss-Italian seemed bored. As Goddard paused for breath, Gregorio got up to bring an end to the briefing. “I haven't finished yet,” snapped Goddard.

Goddard was not the only man looking to change the transfer system. The head of the Argentine tax agency, Richard Echegaray, was also putting pressure on FIFA to take action on what it called “sports tax havens” in South America. Argentine clubs were increasingly routing transfers through small teams in Uruguay and Chile, partly as a way to take dollars out of the country after the country's president Cristina Fernández in 2011 banned individuals and companies from doing so to protect the country's depleted reserves. That year, so-called capital flight had doubled to $22 billion as people sought a safe haven from the tumbling local currency, the peso.

Argentines quickly became jittery at the first signs of a financial crisis, following a 2001 monetary crisis when the government froze bank accounts. Back then, tens of thousands of people took to the streets beating pots and pans to demand access to their savings. Now, at the first signs of financial uncertainty, Argentines stashed dollar bills under their mattresses or in freezers at home. For clubs, footballers and their agents, routing transfers through foreign countries was a way to avoid the government's restriction on storing dollars abroad and it also reduced their tax burden.

The $1.7 million transfer fee for defender Jonathan Bottinelli was wired to a bank account in Miami when he went to River Plate via Union San Felipe, a Chilean team for which he never played, according to the tax agency. Echegaray's agency accused the player of tax evasion in a lawsuit in 2013, a claim that he has contested. Three years later, a trial was still pending at the slow-moving Argentine courts.

In 2014, the tax agency chief travelled to Zurich to tell FIFA president Sepp Blatter about a profusion of similar arrangements. Transfers, he said, had been routed through about a dozen clubs that included a tiny team in Switzerland, 42 miles from Blatter's home town of Visp in a valley below the Matterhorn. The transactions were, he told Blatter, depriving Argentina's treasury of millions of dollars of tax revenue.

FC Locarno was a spectacular drive through the foothills of the Alps from Visp, where Blatter still kept a weekend retreat. The Swiss team had acquired stakes of between 30% and 50% in the transfer rights of five players from River Plate, including striker Gonzalo Higuaín, for $13 million in 2006. The transactions were arranged two days before the end of the transfer window, and allowed the Argentine club to turn a profit for the year. José María Aguilar, the River Plate president, had shrugged when asked why the players had moved to such a small club. “They offered the most money,” he said. “It's a little strange, but it's not our business to investigate.”

Both FIFA and the Swiss football federation had approved the transfers, even though none of the quintet ever actually played for Locarno, which that year played to crowds of as few as 800 locals in the Swiss second division in a modest stadium overshadowed by the foothills of the Alps. The Stadio Lido had a single stand for spectators. There was a sand-filled long jump pit adjacent to one of the goals and a running track skirted the pitch.

The same year as Higuaín ostensibly signed for Locarno, he would instead play in front of sell-out crowds for Real Madrid at its 78,000-seat Santiago Bernabéu Stadium. The Spanish giant paid a transfer fee of as much as $16 million. FC Locarno's president Stefano Gilardi, a dermatologist whose son was the team sports director, said it was getting 900,000 Swiss francs (about $750,000) – money which helped him develop the youth team. Reached at his surgery by telephone, Gilardi said he didn't want to give any more details about the arrangement.

While Blatter's home town was not far away, one of his most senior executives probably had more intimate knowledge of the arrangement: Julio Grondona, the president of the Argentine football federation since 1979, was one of Blatter's closest aides on the world ruling body executive committee. With no interest in becoming FIFA president himself, Grondona had helped Blatter get elected, and was now one of the Swiss's chief supporters. When there was unrest among executives, the Argentine would interrupt: “Gentlemen, why are we arguing? The president is doing a fine job. Let's support the president.”

The man whose first knowledge of accounting came from the books of his family's ironmongery in the Buenos Aires suburb of Avellaneda was now head of FIFA's finance committee. In 2010, it was Grondona that signed off on Blatter's bonus of 11 million Swiss francs for overseeing the World Cup in South Africa. While he still occasionally held court at the Formica tables of a motorway service station his family also owned, Grondona's main domain was his third-floor office of the Argentine federation. His desk was below a wooden cross and a picture of himself with Pope John Paul II, who had started his papacy one year before Grondona's reign.

Known as “Don Julio”, or Sir Julio, Grondona was a supremely dominant figure at the time. At the start of meetings, he would ask his aides the time and they would shoot back: “What time do you want it to be?” He wore a gold ring on his little finger with the inscription “Toda Pasa”, or “Everything Passes”, which he said helped relax him in tense situations.

Grondona had founded Arsenal de Sarandí – it took its name from the London club – in Avellaneda in 1957, and its stadium now bore his name. After becoming president of the Argentine federation, Grondona handed over the running of the club to his son Julio Jr., while he became its honorary president. The club's officials had direct knowledge of the trading through Switzerland. On 25 August 2009, Arsenal de Sarandí brought in midfielder Cristian Pellerano from Switzerland, a country in whose league he had not played a match in his career. Fourteen days later, a new official bulletin by the Argentine federation Grondona oversaw showed that Pellerano had moved to another Argentine team, Colón, again via Switzerland.

Grondona's early years as head of the federation had been intoxicating. In 1986 he had overseen Argentina's second World Cup title, with a thrilling display led by Diego Maradona. According to critics, he and other Argentine football officials had little interest in overseeing the business side of the game. “They are too often seduced by success and sporting glory” said José María Aguilar, the River Plate president. Grondona saw things differently. He said that he welcomed the tax authority's investigation into so-called sports tax havens. “We've always wanted transparency,” Grondona said. “The federation is happy about what's happening.”

Now aged 82, Don Julio was in a frail state and needed an electronic cart to ferry him around Zurich airport after arriving for FIFA business. After being helped into the limousine that delivered him to FIFA's headquarters, Grondona introduced Argentina's tax chief Echegaray to Blatter so that they could discuss the tax-avoiding operations. After showing him a replica of the golden World Cup trophy, Blatter promised he would look into the transfers and get back to him with more information.

Echegaray had also told the FIFA president of what he said were tax-avoiding transfers of Argentine players through Rangers de Talca, a second-division team in the capital of Chile's biggest wine-growing region, known for its Cabernet Sauvignon grape. Ricardo and Sebastian Pini had controlled Rangers de Talca between 2010 and 2014. The brothers signed Argentine defender Santiago Garcia and Colombian midfielder Carlos Sanchez to their modest club, which had not won a major trophy in more than a century.

In email exchanges with us, Sebastian Pini denied that he and his brother were avoiding tax or deliberately exploiting what the Court of Arbitration for Sport said was the loophole in FIFA's rules. He said they were mediators who, thanks to their knowledge of the global football business, had helped the two South American players by unblocking their career paths when they could not come to an agreement with the European clubs they played for: Palermo and Valenciennes. After selling their stake in the Chilean team, the brothers were pursuing another venture. They went to work on behalf of a group of investors in the USA and Switzerland to take over another minor club.

On their radar were Scottish first-division stragglers Motherwell and St. Mirren. Both were for sale. A week before Christmas 2014, Ricardo Pini, a man in his 40s with shoulder-length hair who had recently dated a blonde Argentine TV presenter, turned up at St. Mirren Park in Paisley, near Glasgow, to inspect the 8,000-seat stadium set in an out-of-town industrial estate. With its drab grey frontage, the unprepossessing six-year-old arena looks a bit like a storage warehouse, apart from one thing: the club crest showing it was founded in 1877. The chequered crest is based on Paisley's coat of arms. Pini was invited in through the tall glass doors to speak to St. Mirren directors. The club had a trading loss of £408,000 for the previous year and was an expensive if passionate pastime for its owners, including chairman Stewart Gilmour, who had typed “St. Mirren til I die” on his Twitter account profile.

The meeting helped both sides get to know each other, and St. Mirren director Bryan McAusland said that after a “wee look” at the Argentines they had seemed like decent enough guys. Pini also visited the club's training ground a few miles away, where he saw an Under-20 team game. He was shown a new white inflatable dome hoisted over artificial turf, on which players could train when snow, sleet and ice made the grass fields inhospitable. Two days later, Pini returned to watch last-placed St. Mirren lose 1-0 at home to Motherwell in front of 3,909 fans.

The St. Mirren fans who had missed pre-Christmas festivities to see their team lose to Motherwell and remain at the bottom of the first-division table were mystified by Pini's interest in their club. “I've got one simple question to these guys: why?” John White, the secretary of a supporter group, told the Daily Record newspaper. “If you do not have a St. Mirren background, then why are you here?”

By the end of January, Pini had turned his attention to Girona, a second-division team in northeast Spain. He invited Humberto Grondona, the other son of Don Julio, to watch the team play. Grondona worked as a sports director for Argentina's Under-20 team, after being appointed by the federation led by his own father. While he could not make the game, he said he was more than happy to offer Pini advice about players. In the end, the Pini brothers gave up on acquiring a team in Europe and bought another Chilean team, Union La Calera.

In Zurich, FIFA administrator Goddard was no nearer to closing a loophole that had been exploited since the 1980s. There was nothing illegal in a player signing for a club and then leaving for another, for whatever career-planning reason might be involved.

Argentine tax chief Echegaray was also hamstrung by circumstances outside his control. He said that he had waited a year in vain for Blatter to assist him. He tried another approach: on another trip to Switzerland he visited Michel Platini, president of European ruling body UEFA, and asked for his assistance. Platini would, a few weeks later, announce that he planned to stand in the election to replace Blatter as president. The Frenchman was interested in helping. “If Blatter keeps his promise, that would be welcome,” Echegaray said. “If it's Platini or whoever else becomes president, that would be welcome too.”