Johannesburg, South Africa - The search is on for the two brothers who founded one of the largest crypto exchanges in South Africa after they suddenly disappeared – along with about $4 billion worth of investor-owned Bitcoin.

Authorities the world over are monitoring cryptocurrency exchanges to track whether any of the nearly $4 billion worth of missing Bitcoin is converted or used.

Originally reported by Bloomberg, brothers Ameer and Raees Cajee founded the South African Bitcoin exchange called Africrypt in 2019 and provided substantial returns for their investors.

But last April, investors were informed by the pair that the company had been the victim of a hack. They asked their stakeholders not to report it, so as not to hinder the return of the money.

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Generally, cryptocurrency such as Bitcoin is pretty traceable, which has enabled organizations such as the FBI to recover it when it has been paid out in ransoms. In this situation, being asked not to report the missing money was suspicious enough for the investors to hire attorneys to investigate Africrypt.

Hanekom Attorneys told Bloomberg, "Africrypt employees lost access to the back-end platforms seven days before the alleged hack."

This fact alone indicates the whole thing was more than likely an inside job. Together with another organization, the lawyers forced Africrypt into liquidation.

Investigations showed that the 69,000 coins were moved out of client accounts and "went through tumblers and mixers – or to other large pools of bitcoin – to make them essentially untraceable," according to Bloomberg.

To make an inherently traceable currency invisible, there must have been a lot of planning involved.

The Africrypt website as well as the brothers' phone numbers have been disconnected.

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The matter has been escalated to a special unit of the South African national police called the Hawks, who have informed other exchanges globally to keep their eyes peeled for any activity that could be coming from the two brothers.

Whether or not there was any actual hacking involved, it's cases like this that only act as fodder for lawmakers around the world who seek to criminalize paying ransom payments to hackers.

The incident also does not help improve the image of cryptocurrency to governments that already are wavering on whether or not to recognize crypto investments as valid or legal, particularly when they are prone to volatile fluctuations resulting from anything from a meme to a celebrity Tweet.

If the investments are not recovered then the two brothers will have pulled off the largest crypto heist to date.