Lawyers for the missing co-founders of South African crypto investment platform Africrypt say their relationship with the brothers has been terminated, according to a report from Bloomberg.

Twenty-year-old Ameer Cajee and 17-year-old Raees Cajee are thought to have vanished in April after sending an email to investors telling them the platform had been “hacked,” and shuttering Africrypt’s website. Bitcoin worth an estimated $3.6 billion is allegedly missing.

Johannesburg-based attorney John Oosthuizen, told Bloomberg via email that his firm’s “mandate to assist the Cajee Brothers has been terminated” when asked to comment on the brothers' whereabouts. Oosthuizen’s statement comes only two days after he first spoke with the BBC about the scandal.

The launch of a formal investigation is constrained by South African law, which does not consider cryptocurrencies a financial product. But if the Cajee brothers absconded with the $3.6 billion in bitcoins, the theft would rank among the largest in crypto history.

Oosthuizen previously told the BBC the brothers “categorically denied” the accused heist, saying that it was a hack and the money was missing.

According to Oosthuizen, the reason the brothers didn’t immediately contact the police was not that they were making their getaway but because they are young men with “very little life experience” who were afraid for their lives after receiving death threats from involved parties.