The multi-million dollar fraud scheme had been operating from its Dublin office for a month when Garda fraud squad officers arrested members of the gang travelling by taxi to the Bank of Ireland in College Green, with a potential client in March 1999.
A simultaneous raid was made on the gang's Baggot Street premises where another client was waiting for his appointment with World Wide Clearing and Finance (WWCF). A number of forged bank drafts, including one for $56.5 million, were recovered in the operation.
The conviction yesterday of three of the gang, who were sentenced to a total of 13 years, represents a "landmark" victory for law enforcers combating international fraud, according to Det Supt Willie McGee, based in Harcourt Square.
The Garda operation was unique because the gang was caught while operating from its base office, he said, and the format of the WWCF advance fee fraud had not been previously encountered in Western Europe. The company claimed it would help business people who had already lost money in other Nigerian schemes to recoup their losses.
The WWCF operation was not aimed at Irish people but at foreigners and attempted to entice them to Ireland to deal with the legitimately registered company.
Gardai estimate that up to 50 foreigners had dealings with the gang over the four-week period.
"What should be learned from this is that if it sounds too good to be true, then it isn't true," adds Det Supt McGee.
In the case of the US businessman who gave evidence at the Dublin trial, a $32 million bank draft was offered to him but he was told he would have to hand over $2 million first as a goodwill gesture.
According to detectives what was uncovered was part of a long-running operation dating back to 1993. One witness in the case admitted he had already travelled to Nigeria a number of times and had lost more than £400,000. Det Sgt Ronan Galligan, who headed the investigation into WWCF, said international crime figures suggested that millions of Nigerian "scam" letters were sent annually to people and businesses all over the world.
The Garda fraud squad first became aware that the fraudsters had begun operating in Ireland in October 1998, when two cases of "black money" were seized after searches in the Clonee area of Co Meath.
"Black money" is used as an alternative method of "payment" to bank drafts. The victim is shown a suitcase of black notes and told they are all $100 notes, disguised in a black chemical that enables them to be smuggled out of Nigeria.
The elaborate plan involves telling the victim that the case can only be opened for a few seconds as the chemical will react to air, destroying the cash.
"The sting is when the person pays up to $100,000 for a cleaning chemical for the money. But all they're ever left with is a substance that usually explodes in their fridge and a case full of black paper," says Det Sgt Galligan.
Nigerian letters received by Irish people come in differing versions but all invite the recipient to lodge a large amount of money from Nigeria in their personal or company bank account. A sample of letters sent over the last month included letters purporting to be signed by a government official, the private secretary to the President of Nigeria and the financial controller of the Nigerian National Petroleum Corporation.
Mr Mike Stenger, of the international operations branch of the US Secret Service, yesterday met members of the Garda fraud squad in Dublin. He said the Nigerian schemes first surfaced in the US over 20 years ago and gradually progressed from counterfeit money to credit card fraud to the more recent advance fee schemes.
The view that only greedy people fall for the schemes is not always correct, he said. "Often they target businesses in difficulty and the deal is seen by owners as a last gasp to save their company.
"Many senior citizens have also been victims," he added.