Leston Lawrence worked at the Canadian Mint for over seven years melting gold, purifying it and then testing it. The test samples are scooped out with a ladle and the resulting gold peices (about the width of an Oreo and three time as thick) are then returned to the vat. Or at least, that's how things are supposed to work, but Lawrence smuggled out over 22 of those pucks over the course of 3 months. He even set off the metal detectors while leaving the mint, but the smaller handheld detectors never went off.
It turns out that Lawrence kept latex gloves and Vaseline in his locker and he smuggled the gold out in his backside. The mint's handheld detectors weren't sensitive enough to detect the gold inside of his body.
Lawrence only got caught when a bank teller noticed he was cashing checks from an overseas gold buyer and that he worked at the mint. I guess they need some stronger metal detectors or a more hands-on approach if they want to stop this from happening again.