This was the original dark market, and it became notorious for enabling people to sell drugs and other illegal items online. Law enforcement is also getting better at targeting these dark markets and taking them down. Researchers at Qatar University and the country’s Hamad Bin Khalifa University earlier this week published findings that show just how easy it may be to dredge up evidence of years-old bitcoin transactions when spenders didn’t carefully launder their payments. For vendors, price drops while payments are in escrow might wipe out all the profits from a sale, for instance. But the public ledger of bitcoin transactions known as the blockchain also serves as a record of every bitcoin transaction from one address to another. The funds were always sent in bitcoin rather than fiat currency because when used correctly, the network can provide a great degree of anonymity.