An ex-employee of the top non-fungible tokens (NFT) marketplace has been charged with wire fraud and money laundering, indicating that US law enforcement will no longer ignore the crypto economy.

After being suspected of insider training, Nathaniel Chastain resigned from his position as a product manager at OpenSea, the largest marketplace for NFTs - the unique crypto assets used to represent ownership of objects such as digital art.

Read more: NFTs lose their hype being 'enormously risky'

On Wednesday, he was detained and charged by the FBI in New York in a case that might be alarming for others in crypto who assumed that practices banned in regulated markets were fair game in their sector.

Chastain is accused of exploiting insider information about which tokens would be featured on the top page of OpenSea's website to acquire them just before they were featured and sell them instantly, profiting from the increased visibility each time.

"NFTs might be new, but this type of criminal scheme is not," said US attorney Damian Williams.

Williams explained that "today's charges demonstrate the commitment of this office to stamping out insider trading-whether it occurs on the stock market or the blockchain."

At the time, Chastain's reported deals were noticed. Because of the open nature of the NFT market, where all deals are recorded on a public database known as a blockchain, watchers had seen that someone was acquiring digital assets in September 2021 with dubious timing.

The anonymous digital wallet used for the deals was immediately traced to Chastain's own via transactions. OpenSea had not adopted a specific policy prohibiting such insider trading at the time and responded only after Chastain's trades became public.

An apparent insider trading scheme was uncovered on a leading cryptocurrency exchange in May: a user who has not been identified would build up large positions in small cryptocurrencies shortly before they were listed on major exchanges, then sell them for a profit during the subsequent surge of interest.

According to a Wall Street Journal story, one such deal generated a profit of $140,000 on a $360,000 investment in less than a week.

However, prior to Chastain's arrest this week, there was substantial disagreement over whether such activities were lawful, given the sector's diverse norms and practices. For example, the trading in so-called "shitcoins" – crypto-assets generated with no purpose other than to be purchased and sold in a speculative market – is publicly acknowledged to be full of actions that would be unlawful in a regulated market.

According to the pseudonymous "shitcoin influencer" Epitaph, the latest scheme to enhance the value of cryptocurrencies revolves around "Larp tokens". He defined this as "tokens where the team will go to extreme lengths to convince buyers that they’re connected to famous celebrities/musicians/larger tokens."

“It’s no secret that everything we buy is a scam on some level. The question isn’t ‘is this token a scam,’ because they all are, the question is: ‘Is this scam done well enough to convince other people to buy?’”

Chastain's arrest comes as a group of more than 25 cryptocurrency professionals has sent an open letter to the US Congress for stronger regulation of the sector. “We implore you to take a truly responsible approach to technological innovation and ensure that individuals in the US and elsewhere are not left vulnerable to predatory finance, fraud, and systemic economic risks in the name of technological potential which does not exist,” the group said.

Adding to the regulatory pressure, the Commodity Futures Trading Commission sued Gemini, a New York-based cryptocurrency exchange founded by the Winklevoss twins, on Thursday, alleging that the company misled regulators about the possibility of bitcoin price manipulation in a successful effort to persuade the agency to allow the creation of a bitcoin futures contract.

According to an OpenSea spokesperson, “When we learned of Nate’s behavior, we initiated an investigation and ultimately asked him to leave the company. His behavior was in violation of our employee policies and in direct conflict with our core values and principles.”