Anonymous online sales are surging, and people are dying. Despite dozens of arrests, new merchants -- many based in Asia -- quickly pop up. From a report on the New York Times: In a growing number of arrests and overdoses, law enforcement officials say, the drugs are being bought online. Internet sales have allowed powerful synthetic opioids such as fentanyl -- the fastest-growing cause of overdoses nationwide -- to reach living rooms in nearly every region of the country, as they arrive in small packages in the mail (syndicated source). The authorities have been frustrated in their efforts to crack down on the trade because these sites generally exist on the so-called dark web, where buyers can visit anonymously using special browsers and make purchases with virtual currencies like Bitcoin. The problem of dark web sales appeared to have been stamped out in 2013, when the authorities took down the most famous online marketplace for drugs, known as Silk Road. But since then, countless successors have popped up, making the drugs readily available to tens of thousands of customers who would not otherwise have had access to them. Among the dead are two 13-year-olds, Grant Seaver and Ryan Ainsworth, who died last fall in the wealthy resort town of Park City, Utah, after taking a synthetic opioid known as U-47700 or Pinky. The boys had received the powder from another local teenager, who bought the drugs on the dark web using Bitcoin, according to the Park City police chief.