A gripping new BBC podcast series, The Missing Cryptoqueen, tells the story of Bulgarian tech entrepreneur, Dr. Ruja Ignatova, who vanished in 2017, just as her shady cryptocurrency OneCoin was raking in billions of dollars from investors all over the world.

Up to $5 billion is alleged to have been lost. There are ongoing criminal proceedings in the U.S., OneCoin’s operations were shut down in Italy, and people associated with it have been arrested and charged in China and India.

But despite the disappearance of its founder–whose whereabouts is still unknown–OneCoin is disputing allegations that it’s a scam. And people are still buying its pricey investment “packages,” according to reports last month.

Meanwhile, since the series aired last month, at least one interviewee, who invested in the scheme, has complained of anonymous death threats and taunts over her criticism of OneCoin. A spokesperson for the BBC hinted that it’s been threatened too, adding that the “significant response from OneCoin and its supporters is part of what is revealed in this podcast.”

The OneCoin scheme started at some point in 2014 amid the altcoin boom, which also saw the launch of Dogecoin, Litecoin, Ethereum and more.

Ignatova sold her vision of a new kind of money, superior to Bitcoin, at show stopping conferences during a world tour in 2016.

“She looked like a queen,” one attendee recalled in the first episode of the podcast, which opens with one such event.

The investigation by the documentary team unearthed internal documents revealing the full extent of the scheme. People in 175 countries invested and as much as $500 million came from China.

Meanwhile, OneCoin attracted skepticism from many in the crypto community, who pointed out that: There was no blockchain; the technical claims were wildly inflated; faked videos, false claims and it appeared to use a structure most commonly associated with Ponzi schemes.

Earlier this year, in the U.S, Ignatova was charged in absentia with money laundering, wire fraud and securities fraud.

Crypto lawyer, Preston Byrne has said that, “OneCoin is among one of the more outrageous, flagrant, and long-running alleged scams in the cryptocurrency business.”

And it’s still afloat.