It's a conventional life for a well-to-do Singaporean businessman: he lives in a condo, drives a BMW and enjoys trips to the casino, according to people familiar with his routine. The difference is that Tan Seet Eng - better known in global law-enforcement circles as Dan Tan - is the key suspect in what could be the biggest match-fixing scandal in football history. When news broke this week that nearly 700 games, mainly in Europe, had been targeted by Singapore-linked fixers, questions were immediately raised about Tan, who has been in the spotlight for the past 18 months. His name has cropped up in multiple investigations. In the latest one revealed by Europol, hundreds of players and officials are under suspicion, 14 people have been sentenced and more than 100 prosecutions are expected. But the head of Interpol complains that, while the integrity of the world's most popular sport is under threat, the alleged ringleaders are living freely. Tan, in a rare interview in 2011, vigorously protested his innocence and said that he was mystified as to why he had been accused. "Why I'm suddenly described as a match-fixer, I don't know. I'm innocent," he told Singapore's New Paper . "If there's anything against me, I can take it to court and fight it." Tan, an ethnic Chinese man in his forties, first reached public attention in 2011, when his alleged partner and fellow Singaporean Wilson Raj Perumal was arrested in Finland, convicted of match-fixing and jailed. Perumal, believed to be a key source for blowing open the calcioscommesse (football bet) scandal in Italy, as well as this week's Europol revelations, maintains he was double-crossed by Tan and named him as a key figure in his fixing syndicate. Italian police have issued an arrest warrant for Tan, and court papers quoted by the New Paper called him the "leader" of an international fixing ring. Reports have named him in a German court case and police probes in several countries. According to Perumal, who spoke to the Invisible Dog investigative website last year, Tan was still active as recently as June. "If you arrest Dan Tan, the signal it gives is that investigators can reach out and touch you," said Zaihan Mohamed Yusof, the New Paper 's investigative reporter, who interviewed Tan. But Tan appears to feel secure in Singapore, according to Zaihan, who recounted his routines including trips to the casino. "It doesn't make any sense for him to leave the country, he could be arrested. It's safer for him to be in Singapore," the reporter said. Attempts to contact Tan this week failed. His listed phone numbers are disconnected, and a visit to his home, a run-down condominium next to a suburban shopping mall, proved fruitless. Singapore is considered the nexus of global match-rigging after fixers learned their trade in the local leagues and neighbouring Malaysia. With the birth of online gambling, Singaporean fixers were perfectly placed to take advantage, with contacts in the European leagues and criminal gangs, and in the underworlds of Asia where illicit betting is possible on a huge scale. Last month, Interpol secretary general Ronald Noble said match-fixing generated hundreds of billions of dollars around the world each year, comparing the revenues to multinationals such as drinks giant Coca-Cola. With the pressure now on to smash the match-fixing syndicates, Singapore is squirming in the glare of attention. Its powerful Corrupt Practices Investigation Bureau (CPIB) said "match-fixing of any form is not condoned in Singapore" and that it investigated allegations of game-rigging through bribery. Since 2005, the CPIB had investigated eight such cases in Singapore, with 11 individuals charged and convicted, it said in a statement. However, the CPIB also said it was not involved in matters concerning Interpol. Police in Singapore have confined their comments to a few terse statements saying they are co-operating with Europol and Interpol, including handing over information about Tan. But they said they needed hard evidence to make arrests. "A question that really must be asked is why so little is being done to question Singaporean individuals allegedly involved in such a global match-fixing operation," said Neil Humphreys, a Singapore-based football columnist and the author of the novel Match Fixer . Interpol chief Noble told The Straits Times : "Until arrests are made in Singapore and until actual names, dates and specific match-fixing details are given, these organised criminals will appear above the law, and Singapore's reputation will continue to suffer."