Now, said Willy Allison, a Las Vegas security consultant, casino security teams are often too understaffed to properly wander the casino and monitor “eye in the sky” cameras, particularly since the recession forced layoffs.

One robber turned herself in after more than dozen years in hiding, but authorities failed to hunt down her partner and his windfall.

In 1993, a pair of armed robbers made off with one of the largest bounties - $2.95 million - from an armored car outside the down-market Circus Circus hotel.