Did a hacker or hackers pull off a huge heist from one of the biggest black market drug-selling sites, or did the operators of the anonymous digital narcotics bazaar, Sheep Marketplace, just get away with stealing at least $5.4 million and perhaps as much as $40 million from their clients?Sheep Marketplace and stolen bitcoins After the shutdown of Silk Road in October, Sheep Marketplace became the most popular illicit virtual drug shop. Like Silk Road, Sheep Marketplace was a Deep Web site accessible via the Tor network; customers paid in the digital currency Bitcoins. But by Saturday, Tapscape reported, "It...