Surge in Crypto Seizures Has Cops Hunting for USBs, Passwords

One spring day in a village just west of London, residents saw a man being muscled into a car in front of a nearby house. He reappeared with cuts and bruises 13 hours later, but the cops had already discovered the house was a cannabis-growing operation. A separate search of the man’s home in a nearby town turned up something more intriguing—some of the first cryptocurrency that would ever be seized by U.K. police.

That era-defining 2017 case yielded a safety-deposit box containing jewelry, gold bars, £263,000 ($345,000) in cash, and an item that flummoxed the lead investigator, Matthew Durkin ...