Belfast, Northern Ireland ? On an icy, black Sunday night, police officers brought terrible news to the rural idyll of Kevin McMullan’s home: A relative had just been killed in a car crash, they said. It was a lie — and it launched one of the world’s biggest bank robberies.

Once inside, the phony officers put a gun to McMullan’s head and tied him up, blindfolded his wife, Karen, and then took her away at gunpoint in her own car into the forest.

They told McMullan, a senior executive at Northern Bank in his mid-30s, that he must get the gang into the bank’s major cash vault the next night. If he or another abducted bank official, Chris Ward, 23, refused to help or raised any alarm, their families would be put to death.

Police said Wednesday that the gang got away with more than 22 million pounds, or about $42 million, more than originally estimated. And the 45-strong detective task force admitted it would be hard to track down a gang that left no apparent forensic evidence during their meticulously planned heist.

“This was a carefully planned operation by professional criminals who obviously had done their homework,” Detective Supt. Andy Sproule said.

But despite the smooth operation, money-laundering experts said the gang’s planning had let them down, predicting the thieves would have a hard time using the currency because almost all of the notes were specially produced by Northern Ireland banks.

Sproule said more than $24.5 million worth were new notes bearing Northern Bank’s own design and destined for ATMs, while most of the rest were used notes printed by Northern and three other local banks. Such notes, though denominated as British pounds, aren’t readily accepted in other parts of the United Kingdom or other countries.

Jeffrey Robinson, author of the book “The Money Launderer,” said the gang took too much cash, and of too conspicuous a design, to spend or even hide.

“They obviously did not count on there being so much money, and Northern Irish notes,” Robinson said. “The money is fundamentally useless. I suspect they know that by now.”