Near the beginning of an Italian soccer match in Tuscany on May 23, 2010, a man from Singapore named Tan Seet Eng spoke on the phone with a Croatian associate. He told the associate he needed at least three goals to be scored in the match between Grosseto and Reggina.
"No problem," the associate said, explaining he had someone working for him at the match. With that simple exchange, Italian prosecutors say, the fix was in.
The phone conversation illustrated the power of Mr. Tan, a shadowy figure living in Singapore who was called "the boss" and "the capo" by his accomplices and is suspected of fixing dozens of games as easily as he did that 2010 match in Tuscany.
The game is among about 100 matches played from 2008 to 2011 in Italy's top three soccer leagues that are under investigation — and among 680 matches worldwide considered suspicious by European law enforcement, which reported the results of a 19-month match-fixing investigation last week. European investigators believe Mr. Tan was a common link in many of the matches.
Little is known about Mr. Tan, who is also called Dan Tan. Italian authorities said they were not even sure what he looks like. Their only photo of Mr. Tan is several years old.
"I can't tell you Tan's personality or how he speaks," said Roberto Di Martino, one of the lead prosecutors in Italy's match-fixing investigation. "Tan is a question mark."
Mr. Di Martino added: "I have no idea where Tan takes all the money from, what he does in life. From the picture that we have, he looks like he was 15."
Mr. Tan, who is reportedly in his 40s, could not be reached for comment. A security guard at his last known address, Rivervale Crest, a condominium in a middle-class neighborhood in northeast Singapore, said he moved out several months ago.
Italian authorities issued an arrest warrant for Mr. Tan in November 2011 and forwarded it to Interpol, the international police agency. So far, its search for him has been unavailing.
But the findings of the Italian inquiry — 50,000 pages and transcripts of about 200,000 phone conversations — offer a sketchy portrait of Mr. Tan and how his match-fixing syndicate, as described by the police, flourished for years.
A Simple Business
The syndicate's methods were not particularly complex, investigators said. Mr. Tan and his associates used Milan as a gateway for their endeavors in Italy. They often stayed at hotels near Milan's Malpensa Airport, the Grand Hotel Malpensa and the Crowne Plaza in Somma Lombardo. They even booked the same room on return visits. At the Crowne Plaza, Mr. Tan "has always paid in cash," the report said.
Among Mr. Tan's collaborators were those referred to as the Eastern men — from Eastern Europe. Their boss was Almir Gegic, a former Serbian player. The Eastern men made direct contact with players in hotels where they stayed during training camps. That was where the bribes were made, investigators said.
There was frequent communication between those who dealt with players and the Singaporeans who transported the money for bribes. The most important call was between Mr. Tan and Vinko Saka, a former coach from Croatia who would tell Mr. Tan when a bribe was arranged.
(Read More: Silence in Match-Fixing Probe Puts Singapore at Risk)
"The picture is just not that of simple dishonesty of players and coaches at the local level, but rather one of an operative international network, eased by the 'globalization' of betting on the Internet, capable of convincing disloyal players ready to fix matches and earn easy money," the inquiring judge, Guido Salvini, wrote in a statement.
"This cartel is probably not the only international cartel that works in this criminal field, but it's the first one that has come to light."
The main charge against Mr. Tan in Italy is criminal association targeted to international sports fraud. There are more than 150 people under investigation who face a prison sentence of up to 10 years. Mr. Tan could receive a 15-year sentence if he is found to be the leader of the ring.
"He will certainly be tried in Italy," Mr. Di Martino said. "Most of the people under investigation here will likely plea bargain, but there will most surely be a trial against all those who deny wrongdoing or have not been arrested or found yet."