Operators of two Initial Coin Offerings (ICOs) have gone silent after multiple reports revealed them to be scams that had conned an estimated 32,000 investors of an alleged $660 million in tokens, local news outlet Tuoi Tre News reported Monday, April 9.

Ifan and Pincoin, cryptocurrency startups purportedly from Singapore and Dubai respectively, were allegedly multi-level marketing ponzi schemes under the control of Vietnam-based outfit Modern Tech.

Having gathered what victims claim runs to 15 trln Vietnamese dong (about $660 mln) in token sales, a lack of hard currency payouts prompted a demonstration outside Modern Tech’s Ho Chi Minh City headquarters April 8. If the claim is proven true, the scam would be the largest in the crypto industry to date.

Modern Tech had said it was only an official representative of both coins in Vietnam, before media reports confirmed its seven Vietnamese executives were in fact the masterminds behind them.

According to local news outlet Viet Bao, the owner of Modern Tech’s office building said the company had moved out a month prior in early March.

“Modern Tech left and liquidated a contract about one month ago,” the publication quotes the firm as saying. “No one knows where they are located now.”

Pincoin had been under suspicion online for months. Financial scam directory Behindmlm released an analysis in February 2018 that noted its buy-in method and opaque nature were characteristic of an “ROI ponzi.”

The scheme’s website remains online, along with Ifan’s, which masqueraded as a bridge between celebrities and their fans.