More than $400 million had seemingly vanished into cyberspace... His work—what he calls “blockchain archaeology”—has become an industry... “You know those documentaries about the Kennedy assassinations, and you see them 20 years later?” Mr. Kelman, the lawyer, remembers telling his partners. “That’s going to be us in 20 years.” ... Soon after, he got an unexpected message. Gary Alford, an agent with the U.S. Internal Revenue Service, was known in crypto circles as the investigator who identified the owner of Silk Road, ... Mr. Nilsson passed the name—with a typo—to the IRS agent, Mr. Alford. ... Mr. Vinnik’s future is...