Six Chinese nationals were arrested in Jeju, South Korea, for allegedly assaulting a dealer and stealing $689,000 during a stablecoin exchange.

Authorities in Jeju Island, South Korea‘s largest island, have arrested six Chinese nationals for allegedly stealing 1 billion won (nearly $690,000) during Tether (USDT) transaction at a hotel on Jan. 16, Maeil Business Newspaper reports, citing Jeju Western Police.

The group is accused of attacking the crypto dealer — known just as A — and taking the cash. The suspects, including a man in his 40s — called B —, say they’re the real victims. Police said the group accused A of “making Tether stablecoins disappear” during the transaction. The authorities allege that the group attacked the A person and took the cash meant for the exchange.

Two suspects were arrested at the hotel, the report reads, adding that three others were caught at Jeju International Airport, and one was arrested at another currency exchange. Police recovered 369 million won in cash from the suspects but are still tracking the rest.

The police said all six suspects deny the charges. They claim they originally planned to exchange Korean won for Chinese currency but were convinced to use virtual currency instead. Investigators believe the group always intended to use Tether and think they moved the stablecoins out of the wallet during the exchange before attacking A to steal the funds.

Meanwhile, South Korea’s financial regulator, the Financial Services Commission, has officially started working on the second phase of its crypto rules to boost user protection.

Kim So-young, Vice Chairman of the FSC, said the move to push ahead with phase two comes as the global crypto market faces “rapid changes with mixed feelings of optimism and uncertainty.” The new set of rules will reportedly cover such areas as stablecoins, crypto exchanges, and business entry regulations, though detail are yet to be revealed.