Hackers turned to Tornado Cash as their most-used tool for laundering cryptocurrencies from non-fungible token scams, research firm Elliptic Enterprises wrote in a Wednesday report. 

The platform "was the source of $137.6 million of cryptoassets processed by NFT marketplaces and the laundering tool of choice for 52% of NFT scam proceeds" before the US hit it with sanctions earlier this month, Elliptic said.

Tornado and the likes can help disguise funds by mixing tokens of various origins then transferring them. Crypto mixers laundered $328.6 million in illicit funds over the past five years, according to the Elliptic report. 

Earlier this month, the Treasury's Office of Foreign Assets Control sanctioned Tornado Cash, prohibiting any Americans or US entities from using it. 

And according to TRM Labs, North Korea in particular, has laundered roughly $1 billion in stolen assets through Tornado Cash, also used during the Axie Infinity hack in March. 

Meanwhile, shortly after the sanctions hit, Dutch police arrested a suspected developer behind Tornado Cash, and more arrests may come in the future.