Users of online underground bazaar Sheep Marketplace are trying to figure out who got away with $5 million, $40 million, or even $100 million worth of bitcoins from the site — and whether it might be the owners themselves. Yesterday, Reddit user CrazeeFruito posted a message from the front page of Sheep Marketplace, which appeared to have been shut down.

Sheep is down We are sorry to say, but we were robbed on Saturday 11/21/2013 by vendor EBOOK101. This vendor found bug in system and stole 5400 BTC — your money, our provisions, all was stolen. We were trying to resolve this problem, but we were not successful. We are sorry for your problems and inconvenience, all of current BTC will be ditributed to users, who have filled correct BTC emergency adress [sic]. I would like to thank to all SheepMarketplace moderators by this, who were helping with this problem. I am very sorry for this situation. Thank you all.

With bitcoins hovering around $1,000 apiece, that meant that "EBOOK101" had effectively stolen over $5 million from users. Bitcoin owners have experienced serious hacking losses before: last year, exchange site BitFloor had 24,000 bitcoins (then worth a mere $250,000 USD) stolen because of a security hole, and a little over 1,000 bitcoins went missing from virtual wallet BIPS last month. But users had serious doubts that an outsider had really found and exploited a bug, especially after what was described as a week of suspicious behavior. In late November, the site SheepMarketScam.com started warning readers that vendors and buyers couldn't withdraw money from Sheep Marketplace. At the same time, it said that market moderators had started offering bulk drug purchases if people would pay first rather than keeping the money in an escrow account.

"All day, we've been chasing the scoundrel with our stolen bitcoins."

"They know Sheep is closing and so they are reducing all prices, introducing new products, and making everyone [finalize transactions early] to try and take as much as they can," wrote the author. And the actual theft is thought to be much higher than 5,400 bitcoins. As noted by Tapscape, Andy Greenberg of Forbes, and others, some people have pointed to an address with transactions totaling a little over 39 bitcoins, supposedly the amount in Sheep Marketplace before it shut down, as an indication that the site's owners had absconded with the funds.

On Reddit, a pair of users have worked to follow a trail of allegedly stolen bitcoins as they're bounced around addresses for laundering. "All day, we've been chasing the scoundrel with our stolen bitcoins through the blockchain," wrote sheeproadreloaded2. The money they're chasing, which is still being moved through accounts, is closer to a total of 96,000 bitcoins, and users hope that knowing where it's gone will help identify the thieves if they try to sell or convert their ill-gotten gains. Overall, though, the whole shutdown is a confusing mess, and it's far from clear even how much has been stolen, regardless of who took it or whether this hunt will help solve the mystery.

While some hope to track down the people behind the theft, others wonder if the site's owners are starting a new scam. SheepMarketScam.com writes that Sheep Marketplace started linking a service called TorMarket, which the author suspects is run by the same people. TorMarket, however, has disavowed the site and asked its administrators to take down the link. "This is the worst PR we can get right now," its home page reads. For users who moved to Sheep Marketplace from Silk Road after its shutdown by law enforcement, this means another major bitcoin black market is gone, along with their money.