A pair of South African brothers have vanished, along with Bitcoin worth $3.6 billion from their cryptocurrency investment platform. A Cape Town law firm hired by investors says they can’t locate the brothers and has reported the matter to the Hawks, an elite unit of the national police force. It’s also told crypto exchanges across the globe should any attempt be made to convert the digital coins. Following a surge in Bitcoin’s value in the past year, the disappearance of about 69,000 coins — worth more than $4 billion at their April peak — would represent the biggest-ever dollar loss in a cryptocurrency scam. The incident could spur regulators’ efforts to impose order on the market amid rising cases of fraud. The first signs of trouble came in April, as Bitcoin was rocketing to a record. Africrypt Chief Operating Officer Ameer Cajee, the elder brother, informed clients that the company was the victim of a hack. He asked them not to report the incident to lawyers and authorities, as it would slow down the recovery process of the missing funds. Some sceptical investors roped in the law firm, Hanekom Attorneys, and a separate group started liquidation proceedings against Africrypt.