The $2 million figure was taken from what I heard on NPR. I haven't been able to find a really good article on the web about the robbery. And while the idea is far from new, its just that it worked out. While the bank had the right sensors, there wasn't anything the cops could do about the fact that...

http://www.csmonitor.com/World/Americas/2011/0104/Argentina-bank-heist-echoes-Woody-Allen-films-and-Sherlock-Holmes-tales The thieves spent 6 months digging a 100 foot long tunnel from a nearby building, broke through into the safety deposit room, and robbed the place over a holiday (but apparently ...