Around 30 people have been formally charged in Japan with trading almost $100 million worth of digital assets while knowing they had been stolen three years ago.

According to a report by Japan's Mainichi on Friday, authorities in Japan allege the people were found to have been exchanging NEM's XEM cryptocurrency for other cryptocurrencies via an illicit exchange on a darknet marketplace.

The stolen cryptocurrency is a portion of the $560 million worth of XEM and other cryptocurrencies siphoned off the Tokyo-based Coincheck exchange in a massive January 2018 hack.

The 30 individuals are alleged to have traded more than 10 billion yen (US$96 million) based on the exchange rate at the time of the theft when XEM was around its all-time high of $1.6. Prices today are well below that at around $0.21, according to CoinMarketCap.

Some of the suspects involved in the arrest allegedly exchanged their illicitly traded digital currencies for fiat currency at various legal exchanges in Japan and overseas, netting large profits.

The identities of those who hacked Coincheck still remain unknown.

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The Tokyo Metropolitan Police Department will soon finalize its probe into those that exchanged the stolen tokens as the statute of limitations is approaching, according to Mainichi's report.

Two individuals whose trading volumes greatly exceeded others were arrested in March 2020, while the other suspects were charged a later date. The 30 are residents of Japan and have been referred to prosecutors following the charges.