In October, Citibank received two dozen faxed requests for money to be wired, and it transferred $27 million to accounts controlled by the conspirators in Japan, South Korea, Australia, China, Cyprus and the United States, the complaint says.
Citibank called the officials whose names and numbers it had been given to verify the transactions, prosecutors said. The numbers turned out to be for cellphones in Nigeria, South Africa and Britain used by the conspirators.
Citibank, in its investigation, later determined the package of documents had come via courier from Lagos, Nigeria, rather than from the offices of the National Bank of Ethiopia, in Addis Ababa.
Citibank has credited back the lost funds to the National Bank of Ethiopia, said one person who was briefed about the situation.