See, once they got in there, they welded the vault's door shut from the inside and presumably donned their striped sailor shirts and red berets while laughing like "oh-hoh-hoh-hoh," busting out the bread, cheese, and pate, and having themselves a full-on Frenchman party. They popped bottles of wine and drank it from priceless chalices; when the urge struck, they dropped big ol' deuces into antique silver tureens. Oh, and somehow, during all that, they also found time to break into hundreds of safety deposit boxes and retrieve "$8 million to $10 million in gold, cash, jewelry and gems."
As might be expected with such a ridiculously audacious crime, it didn't take authorities long to catch up with Spaggiari and force a confession out of him -- but they hadn't seen "audacious" just yet. While at the magistrate's office, he complained about the heat and asked if he could open a window. When his wish was inexplicably granted, the Spagster jumped out the window, landed on the roof of a car 10 feet below, then hopped onto the back of a speeding motorcycle, presumably throwing up an exaggerated bras d'honneur as he zoomed away.
He was sentenced to life in prison in absentia, which is sort of like that dinner invitation from your weird uncle in Detroit (as long as you never bother going there, you never have to deal with it). And just to rub salt in the wound, he would eventually use all the free time he found while relaxing at his Argentine villa (purchased with the proceeds from the heist) to write a book all about it.