The U.S. Department of Justice is looking into the alleged hack that saw $370 million drained from crypto exchange FTX hours after it filed for bankruptcy.

A person familiar with the case told Bloomberg on Tuesday that the DOJ has launched a criminal probe into the FTX hack. The person said that U.S. authorities have managed to freeze some of the stolen funds, albeit a small portion of the total amount.

The criminal probe is separate from the host of fraud charges brought by the DOJ against former FTX CEO Sam Bankman-Fried.

The hacking event in itself has roused a considerable amount of suspicion from industry watchers. The general consensus among blockchain security experts who analyzed the flow of funds is that the hack was likely the work of an FTX insider.

Dyma Budorin, co-founder of blockchain security firm Hacken, told CoinDesk last month that the hacker had access to all the cold storage wallets that they exploited. The hacker also used a KYC-verified account on crypto exchange Kraken to fund one of their wallets – something Budorin described as “a stupid mistake.”

The theory that the hack was an inside job is one that Bankman-Fried seemingly agrees with. In aan Nov. 30 interview with Tiffany Fong, Bankman-Fried said he had “a pretty decent sense” that the hack was the work of an FTX employee, or someone who installed malware on an employee’s computer.

Many in the crypto community believe that the hack was orchestrated by Bankman-Fried himself, potentially with the help of associates operating under his direction. 

“Probably the same guy who wrote codes to ensure a margin call did not occur for certain accounts,” tweeted one user on Tuesday.