By Suvashree Ghosh, Anders Melin, Ben Weiss and Muyao Shen

At a small cryptocurrency shop in the heart of Kuala Lumpur, a sheet of paper dated Oct. 10 is taped to shutters over the entrance: “Our physical stores are temporarily closed until further notice.”

Malaysian retailer CryptoBilis, a reseller of hardware crypto wallets, has become a focal point of an investigation into thefts from devices meant to secure digital assets offline. Customers began reporting missing funds on Oct. 9, and blockchain researchers have estimated losses of over $90 million.

Paris-based Ledger SAS, manufacturer of the affected wallets, said on Thursday that a “highly organized criminal group” had fitted some of its devices with hidden hardware….