Unofficial investigations into money laundering at defunct cryptocurrency exchange Mt. Gox alleged that a UK “shell” company was involved in laundering 650,000 BTC (equal to about $6.9 bln at press time) March 7.

According to an expose by File On 4, a program on the BBC’s news and current affairs radio station Radio 4, the Always Efficient LLP company participated in processing the funds hacked from the Tokyo exchange.

Also the subject of the ongoing official FBI operation, Always Efficient LLP purports to be based in London, yet its address is “shared by several other companies” and is “likely to be a shell,” Duncan Hames from anti-corruption group Transparency International told the broadcaster.

“People laundering money will set up a network of companies to create layers between the original crime and their attempts to then integrate the proceeds of their crime into the economy,” he claimed.

Cointelegraph previously reported on how a Europe-based exchange, BTC-e, became the focus of the Mt. Gox inquiry into the laundered funds.

The exchange has since rebranded, but its alleged former operator Alexander Vinnik remains in custody. Vinnik denies involvement in Mt. Gox.

Meanwhile, trustee and bankruptcy attorney for Mt. Gox Nobuaki Kobayashi has reportedly sold over $400mln in BTC since September 2017 with an eye to crediting customers who lost funds during the hack.