The U.S. Department of Justice is investigating the two brothers behind Solana stablecoin exchange Saber Labs, Ian and Dylan Macalinao, according to two people familiar with the matter.

The investigation follows CoinDesk’s August report that the Macalinao brothers used a web of 11 pseudonymous identities to build an ecosystem of interlocking financial products that double- and triple-counted crypto deposits by passing tokens between themselves. Their effort boosted a key growth metric for Solana by billions of dollars during the height of crypto’s 2021 bull market, and, according to Ian, juiced the price of SOL, the native token of the Solana network.

“The metric to optimize for in Summer 2021 was [total value locked (TVL)],” Ian wrote in a never-published blog post obtained by CoinDesk. “TVL can only count if protocols are built separately, so I devised a scheme to maximize Solana’s TVL: I would build protocols that stack on top of each other, such that a dollar could be counted several times.”