Two South African brothers have allegedly vanished with bitcoin worth $3.6 billion that was housed on their cryptocurrency investment platform.

According to various reports, a local law firm, Hanekom Attorneys, hired by affected investors, says it cannot find Ameer and Raees Cajee, the founders of Africrypt.

Hanekom Attorneys said it has reported the incident to the Hawks, an elite unit of South Africa’s national police force.

The firm has also warned crypto exchanges around the world to be on the lookout should anyone try to sell the digital currency on their platforms.

The brothers have said to have disappeared with 69,000 bitcoins and are believed to have fled to the United Kingdom.

The brothers are reported to have set up their crypto investment service, Africrypt, in 2019.

But in April, as the price of bitcoin surged to an all-time high, Ameer, who serves as a chief operating officer of Africrypt, sent an email to investors telling them that the company had been hacked.

Ameer made an unusual request, asking clients not to report the incident to authorities or lawyers, saying that it would slow down their efforts to recover from the hacking.

But a group of skeptical investors contacted Hanekom Attorneys, “which focuses on all aspects of the cryptocurrency industry” and advises “large-volume traders, exchanges and arbitrage companies.”

“We were immediately suspicious as the announcement implored investors not to take legal action,” Hanekom Attorneys told Bloomberg.

“Africrypt employees lost access to the back-end platforms seven days before the alleged hack.

This is the second big loss to hit South African cryptocurrency investors in the last two years, with Johann Steynberg, CEO of trading platform Mirror Trading International, disappearing with 23,000 bitcoins.