A Bulgarian woman who is wanted by the FBI for an alleged scam involving cryptocurrency was in Ireland before she vanished, according to a British journalist who has been searching for her for years.

Dr Ruja Ignatova is accused of defrauding investors out of $4bn (£3.3bn) by selling a fake cryptocurrency called OneCoin.

The FBI recently added Dr Ruja to its 10 most-wanted fugitives list and is now offering a $100,000 reward for information leading to her capture.

British journalist Jamie Bartlett is the author of The Missing Cryptoqueen, and the star of the BBC podcast with the same name.

He spoke to the Indo Daily about the illusive Dr Ruja, who he described as one of the “richest criminals of all time”, and her connection to Ireland.

Mr Bartlett said Dr Ruja was originally indicted by US officials two weeks before she disappeared.

“I think she may have been in Dublin a couple of weeks before she was arrested as well, and no one knows why and no one can be sure.

“So, if anyone was in Dublin October 2017 and vaguely remembers her, please get in touch.”

He continued;

“She’s a German-Bulgaria businesswoman, who basically turned up in 2014, aged 34, saying to the world you’ve heard of Bitcoin, you’ve seen everyone getting rich from Bitcoin, the cryptocurrency that’s going to revolutionise money and you’ve missed the boat with that one. But the good news is that I’ve got a better one. It’s called OneCoin. It’s simpler, it’s clearer, it’s early. So, if you invest now, the price of this will keep going up,” he said.

Mr Bartlett said by 2016 OneCoin “captured the imagination” of investors around the world and over 1 million people, from 175 countries invested roughly $4 billion in the product.

However, the investors never got the payoff which Dr Ruja repeatedly promised and by October 2017 she disappeared.

Mr Bartlett said Dr Ruja modelled herself as a type of messianic figure, but what she really created was a “sophisticated pyramids scheme”.

He said she escaped with at least $500 million.

“It seems possible that she may have actually made a very clever deal back in 2015 to trade her company for 230,000 Bitcoin, which at the time was worth $50 million but at the moment is worth something like $4 to $5 billion,” he said.

“If she did that, and she’s still holding onto those Bitcoin, I mean we’re now talking about someone who’s one of the richest criminals of all time. So, I don’t know if she spent a lot of that money because to hide, to be protected; that’s expensive.

“You need to keep paying people off. So, she may have burned through a lot of money as well.”

OneCoin was essentially a “multi-level marketing” scam according to Mr Bartlett, where people would buy thousands of euro worth OneCoin and then recruit others to also buy the cryptocurrency. He said while people could never cash out their OneCoin, they would get a some commission for recruiting others.

“Each time that happened a small commission would make its way up the pyramid but we’re selling sort of thin air to people,” he said.