If the cases are ever compromised or the thief happens to enter at exactly the right time, as he did at the Carlton, the outer perimeters should be able to halt the thief's progress. "A commander should know where each security guard is," Roman said. "They should immediately know there's a robbery in place and should have a plan to interrupt it. ... If he gets in, he's not getting out." Strong coordination with local authorities—which were not even aware of the Carlton exhibition—could be especially beneficial in this case. A nearby officer could have responded to calls over a radio, and stopped the thief as he hit the sidewalk.

The marketing of the event also seemed a bit hapless. Large, splashy pink signs on the front of the hotel advertised the valuable Leviev wares and the month-long exhibition. John J. Kennedy, the president of the New York-based trade association Jewelers' Security Alliance, which advises law enforcement agencies on such matters, suggested that, at minimum, the event should have been held in an upstairs room, with security checking in registered guests at the door. And given the extraordinary price of the pieces, organizers should have only enlisted trustworthy, local jewelers to invite clientele capable of buying them. "To market it in that way is really reckless," Kennedy said. "You don't market 64 carat diamonds with a sign on the outside of a hotel."

***

Despite the confluence of security defects, no one believes the "lone" gunman was really operating alone. The timing of the crime was too perfect, the escape out of the window too quick, and the prospect of moving such an easily recognizable product too overwhelming.

The speed and precision with which the thief executed the operation indicates that someone had meticulously "cased" the hotel and the exhibition room. "It didn't just happen willy-nilly," Kennedy said.

And once he was on the run, the thief had to have somewhere to go. "He needed transportation," Roman said. "He needed a change of clothes. He needed a safe house. All of that requires some assistance. I'm sure he had accomplices."

The identities of the bandit and his potential accomplices are still unknown. But theories about a link to the jewel-snatching syndicate the Pink Panthers, a organized crime group with hundreds of members and roots in the former Yugoslavia, began surfacing in the press almost immediately after the heist.

They certainly have the audacity to pull something like this off. The band of thieves and its contractors—many of whom are thought to have received paramilitary training during the Balkans conflict of the 1990s—have stormed into and held up hundreds of pricey jewelry boutiques in 35 countries. The organization has made off with more than $430 million worth of jewels since 1999, according to INTERPOL, which has an entire project devoted to helping the law enforcement agencies exchange intelligence to track and catch the perpetrators.