Italian court documents show he stayed in the country just 6 hours and 30 minutes, never left the airport, and then boarded a return flight to Singapore.
Why such a quick hop across the globe?
Italian authorities believe it was to deliver bribe money. They allege the suspected courier, who was under surveillance, delivered information and cash on behalf of a crime syndicate that fixes soccer matches.
EDITOR'S NOTE: This story is part of a six-month, multiformat AP examination of how organized crime is corrupting soccer through match-fixing.
Italy, a four-time World Cup-winning football power, has become so blighted by match-fixing that Premier Mario Monti has even suggested halting the professional game for two to three years to clean it up.
Italian prosecutors investigating dozens of league and cup games they say were fixed have followed a trail back to a figure who is thought to be in Singapore. In documents laying out their findings, prosecutors alleged that 48-year-old Tan Seet Eng is the boss of a crime syndicate that allegedly made millions betting on rigged Italian games between 2008 and late 2011, through bribing players, referees and club officials.
Italian authorities have issued an arrest warrant for Tan and list him as their No. 1 suspect, but they have been unable to take him into custody.
"Tan Seet Eng, nicknamed Dan, surfaces in all the European investigations examined, including the Italian one, so therefore he constitutes a common thread that links each criminal gang together," prosecutors stated in a 340-page court document detailing their investigation, which has been leaked to Italian news media. "He directs the aforementioned criminal gang."
Italian authorities have about 150 people under investigation, including Tan, but have yet to indict any of them, prosecutor Roberto Di Martino told The Associated Press last month. Italian arrest warrants cannot be served on Tan while he is in Asia.
Di Martino, who is leading the investigation from Cremona in northern Italy, said Tan will "almost certainly" go on trial in Italy, but likely in absentia. Italy has no extradition treaty with Singapore, but the Italian Justice Ministry said the Asian city-state could still send over a wanted suspect under "friendly terms" if it chooses. Di Martino said relations with Singapore authorities "have not been great. We had hoped for more."
"At first we actually thought they could be brought to Italy, but that calculation was wrong," Di Martino said. "If Tan Seet Eng goes somewhere else, he could be extradited, as long as there's an extradition treaty with that country."
In Singapore, police spokeswoman Chu Guat Chiew said authorities there are reviewing the information submitted by the Italians before deciding what to do, adding: "So far, Dan Tan Seet Eng has not been charged with any offence in Singapore."
Police have questioned dozens of people in Italy, searched the homes of players and coaches, and descended on the Italian national squad's training camp early one morning in May 2012. But Di Martino said the investigation has turned up only limited information about Tan.
"We don't know much about him. We don't know if he's a legitimate businessman involved in illegal activity, or if he's involved in money laundering," Di Martino said. "We're only interested up until a certain point; then it's Singapore's problem."
Much of what European law enforcement authorities have learned about Tan comes from a former associate, Wilson Raj Perumal. A match fixer, also from Singapore, he was arrested in Finland in February 2011, convicted and sentenced to two years in prison for bribing Finnish league players. To Finnish police, Perumal portrayed the syndicate as a well-oiled and structured business, financed and led from Singapore.
The syndicate mainly places bets in China, Perumal said, according to a transcript of his May 18, 2011, police interview obtained by the AP. He said the group fixed "tens of matches around the world" - in Europe, Africa, the Middle East and the Americas - from 2008 to 2010. He estimated the group's total profits after expenses at "several millions of euros, maybe 5-6 million" - $7 million-$8 million.
The syndicate leader decides which matches to fix and how much to wager, organizes the betting and drops off bribe money, Perumal said in the transcript. He later identified that leader as Tan, according to the Italian court documents. Italian police traveled to Finland to interview Perumal, Di Martino told the AP. Perumal declined AP requests for an interview.
Perumal told the Finnish police that money was transported from Singapore in couriers' pockets or on their bodies. Italian prosecutors suspect the quick trip to Milan's airport was one such drop. The suspected courier's checked luggage weighed 9 kilograms in Singapore but 8 kilograms when he flew back. They said the suspected courier likely delivered "a sum of money hidden in some sort of container, which was destined to finance the organization's illicit activity."
AP could not contact Tan in Singapore. Five phone numbers identified as his by Italian prosecutors were disconnected. No one answered the door at an apartment the Italians listed as his address. Mail and flyers stuffed under the door and in the door frame suggested no one had been there for a while.
The New Paper in Singapore reported that it spoke to Tan in 2011.
"Why I'm suddenly described as a match-fixer I don't know. I'm innocent," it quoted him as saying. It quoted Tan as saying he was briefly involved in a business venture that Perumal started, "but I took my name out of the company after I smelled something fishy."
"Maybe that's why he had named me to investigators," he continued. "Anybody involved with Wilson gets bad luck. He has a criminal record. It's not good for Singaporeans to do business with him."
Perumal alleged to Italian investigators that Tan places syndicate wagers on fixed games using legal, Asia-based online betting sites - he named three of them - via intermediaries in China. In Shenzhen, a southern China city adjacent to Hong Kong, a 1 million euro wager on a game in Serie A, the top Italian league, can be placed this way in a couple of minutes, he told the Italians. That method matches those described by betting experts.
Investigators say such gambling operations hire workers to rapidly place thousands of small online bets - maybe no more than $1,000 each - on fixed games. The scattershot of small bets, rather than several large ones, can help hide fixes from monitoring companies in Europe that use computer software to look for unusual wagering.
"They employ kids and they employ people in Singapore and Malaysia to do that for them," said Chris Eaton, former head of security for FIFA, soccer's governing body. "They virtually have a sweatshop, if you like, of people with a large number of credit cards and laptop computers, and they punch those things when they are given the green light."
"Dan Tan comes with very good Oriental connections, meaning he's not running as a single financier. He has an organization behind him," said Eaton, now director of sport integrity at the International Centre for Sport Security, a Qatar-backed group funding efforts to research the extent of match-fixing and ways to combat it.
Eaton's successor as FIFA security director, Ralf Mutschke, said last year that the news media have overstated Tan's alleged role in match-fixing, and that he probably isn't "as involved as everyone is thinking" and has only "symbolic importance."
"But you give him a name, so everyone is talking about Dan Tan, and Dan Tan syndicates, and Dan Tan here and Dan Tan there," Mutschke said. "If we kill Dan Tan then you will have no match-fixing? No, I think it's not as easy as this."