Authorities are searching for two business partners who allegedly misused investor funds to buy their way into crypto billionaire-hood.

South Africa’s Finance Sector Conduct Authority (FSCA) is trying to track down Africrypt founders Ameer and Raees Cajee. The brothers are accused of defrauding customers through using their money to purchase $3.6 billion in Bitcoin cryptocurrency and disappearing.

The Cajees first established Africrypt as a crypto investing app in 2019 and quickly amassed funds through promising users a healthy return on investment. However, the app never delivered on its promise.

Investors first suspected something was wrong when company employees reported being unable to access the website back-end. A week later, they received an email that the trading platform suffered a cyberattack that drained users of their accounts, wallets, and nodes.

Company CEO Ameer asked customers not to report the cyberattack to police or lawyers because complaints would only slow down the fund recovery process. Phone calls to the founders were automatically forwarded to voicemail, and the Africrypt website was still offline at the time of publication.

First National Bank (FNB) claimed it only banked Africrypt and denied any involvement or wrongdoing.

“FNB once again confirms that it does not have a banking relationship with Africrypt,” FNB’s risk spokeswoman Nadiah Mahara said according to the Independent Online. “Due to client confidentiality, FNB cannot provide any information on specific bank accounts.”

Multiple investors have appointed law firm Hanekom Attorneys to pursue the brothers.

“We were immediately suspicious as the announcement implored investors not to take legal action,” the law firm said in a statement obtained by the New York Post. “Africrypt employees lost access to the back-end platforms seven days before the alleged hack.”

Recovering what is left of the money has proven difficult as the Cajees allegedly transferred pooled amounts from different bank accounts, client wallets, and Bitcoin transactions to make them difficult to trace.

FSCA has faced delays in launching an official investigation since Bitcoin is not recognized as a legitimate financial product across the Rainbow Nation.

A South African judge recently ruled in favor of about 20 investors and handed down a provisional liquidation order to Africrypt. The brothers have until July 19 to object to liquidating their assets and distributing the proceeds to creditors.

Crypto-related crimes have increasingly concerned regulators and businesses alike. Chainalysis’s latest Crypto Crime Report revealed the value of funds involved in illicit activity exceeded $10 billion so far in 2021. This figure has dramatically decreased since 2019.

U.S. Treasury Secretary Janet Yellen (D) previously expressed concerns that cryptocurrency might be used for unlawful purposes.

“To the extent it is used, I fear it is often for illicit finance,” she said according to Markets Insider. “I do worry about potential losses that investors can suffer.”