Dr Declan Hill is the author of 'The Fix: Organized Crime and Soccer', about Asian match-fixers.

BBC: Viewpoint: The murky world of illegal Asian gambling

Singapore's investigation of Mr. Tan "is a good start" but tougher action needs to be taken against the alleged match-fixers, said Declan Hill, an academic and investigative journalist who has reported extensively on global match fixing.

WSJ: Singapore Says Suspect Is Helping Soccer Probe

Declan Hill, author of "The Fix, " a book that saw him spend time with Asian betting syndicates and match fixers, believes that the proliferation of football and technology means that match fixing is now both incredibly easy and virtually untraceable.

CNN: STORY HIGHLIGHTS