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Ruja Ignatova strode onto the stage in a flowing burgundy ball gown adorned with black sparkles. Beams of light flashed, fireballs erupted and Alicia Keys’ “Girl on Fire” blared through the speakers.

“Looks like a girl, but she’s a flame. So bright, she can burn your eyes – better look the other way,” the song crooned as a beaming Ignatova thanked the cheering crowd at London’s Wembley Arena.

That was in June 2016, when cryptocurrency was an emerging buzzword and investors were scrambling to cash in. Ignatova called herself the “Cryptoqueen” and touted her company, OneCoin, as a lucrative rival to Bitcoin in the growing cryptocurrency market.

“In two years, nobody will speak about Bitcoin anymore,” she said, as investors applauded and whistled.

Sixteen months later, Ignatova boarded a plane in Sofia, Bulgaria, and vanished. She hasn’t been seen since.

Authorities say OneCoin was a pyramid scheme that defrauded people out of more than $4 billion as Ignatova convinced investors in the US and around the globe to throw fistfuls of cash at her company. Federal prosecutors describe OneCoin as one of the largest international fraud schemes ever perpetrated.

She is now one of the FBI’s 10 most-wanted fugitives, alongside accused gang leaders and murderers, and is the only woman currently on that list. Of the 529 fugitives on the FBI’s list since it launched in 1950, she’s one of just 11 women.

Ignatova and her partners “conned unsuspecting victims out of billions of dollars, claiming that OneCoin would be the ‘Bitcoin killer,’” US Attorney Damian Williams, New York’s top prosecutor, said in a statement last month.

“In fact, OneCoins were entirely worthless … (Their) lies were designed with one goal, to get everyday people all over the world to part with their hard-earned money.”

Since Ignatova disappeared in October 2017, her face has been plastered on the FBI website and across major news outlets worldwide. She’s also one of the most wanted fugitives in Europe.

At the bottom of her FBI wanted poster is a note: “Ignatova is believed to travel with armed guards and/or associates. Ignatova may have had plastic surgery or otherwise altered her appearance.”

The FBI says it picks fugitives for the list based on the length of their criminal records and how dangerous they may be. It also favors fugitives who are not well known to maximize the benefit of the program’s nationwide publicity.

The bureau declined to provide additional details to CNN beyond court documents from the US Department of Justice, which did not list an attorney for Ignatova. “This case is an ongoing investigation. We are unable to comment beyond what has already been released publicly,” said Daniel Crifo, a spokesperson for the FBI office in New York.

But court documents detail a mind-blowing narrative: how Ignatova and her OneCoin co-founder, Karl Sebastian Greenwood, were allegedly aware from the start that their ambitious venture was a Ponzi scheme.

“The cryptocurrency OneCoin was established for the sole purpose of defrauding investors,” IRS Special Agent John R. Tafur said in a statement.

While Greenwood and Ignatova were working on the concept for OneCoin, they referred to it in emails as a “trashy coin,” federal officials said in court documents. The documents show Greenwood described their investors as “idiots” and “crazy” in an email to Ignatova’s brother, Konstantin Ignatov, who also took part in the scam and assumed OneCoin leadership after his sister vanished, according to prosecutors.

“It might not be (something) really clean or that I normally work on or even can be proud of (except with you in private when we make the money),” Ignatova wrote to Greenwood in 2014.

She also proposed an exit strategy should the company fail, saying in a 2014 email to Greenwood that they should “take the money and run and blame somebody else for this.”

Ruja Ignatova, 42, is a German citizen but was born in Bulgaria, where her father was an engineer and her mother was a teacher.

In his book, “The Missing Crypto Queen,” author Jamie Bartlett detailed her rise from modest beginnings to entrepreneurial stardom.

When she was a girl, her family moved to Germany, where Ignatova excelled as a student and spent her free time studying and playing chess, Bartlett wrote. Classmates described her as smart, driven and aloof.

Ignatova won a scholarship to a university in Konstanz, Germany, where she met and married a fellow law student. She maintained she didn’t want children, Bartlett wrote, because they would get in the way of her acquiring wealth.

She also told people she wanted to be a millionaire by age 30.

“She desperately wanted to be rich, even devouring books in the early hours about how to make money,” Bartlett wrote.

After studying European law at Oxford University, Ignatova landed a job in Sofia as a consultant for McKinsey & Company, the international management consulting firm.

Clients trusted her and related to her rise from humble beginnings and fierce desire to be rich, Bartlett wrote. Her fluency in languages, including Russian, German, English and Bulgarian, also helped.

Appearances mattered to Ignatova, who often attended events in evening gowns and bright red lipstick, with diamonds dangling from her ears.

“Everything exhibited success and glamor,” Bartlett wrote. “She was obsessed with style and image.”

Cryptocurrencies such as bitcoin are digital assets created and managed by a global, decentralized network of computers instead of a bank or government. Bitcoin, for example, is “mined,” or created, by professional crypto miners using armies of servers in data centers.

It is a largely unregulated and highly volatile industry, and expert opinions on the viability of crypto run the gamut. Advocates broadly envision a future in which economies run on digital currencies validated by the community of users rather by a central bank. Critics dismiss it as a Ponzi scheme or, at minimum, a highly risky investment.

In 2014, Ignatova and Greenwood, her co-founder, started pitching OneCoin to investors in Europe, New York and around the world. They hosted online webinars and conferences where they urged potential investors to deposit funds in an account that would enable the purchase of OneCoin packages, according to a federal indictment.

OneCoin operated as a multilevel marketing network in which investors received commissions for recruiting others to buy cryptocurrency packages, federal prosecutors said. The packages catered to various income levels, from “starter” to “tycoon trader.”

Ignatova and her partners promised buyers a fivefold or even tenfold return on their investment, according to court documents.

A buying frenzy ensued. Between the fourth quarter of 2014 and the fourth quarter of 2016 alone, investors gave OneCoin more than $4 billion, federal prosecutors said, citing records obtained in the course of their investigation. Some $50 million came from investors in the US, according to court documents.

“She timed her scheme perfectly, capitalizing on the frenzied speculation of the early days of cryptocurrency,” said Williams, the top federal prosecutor in Manhattan.

OneCoins were not mined like other cryptocurrencies, federal investigators said. Instead of armies of powerful servers, OneCoin was generated by a piece of software, court documents said.

Federal prosecutors said that in an email to Greenwood in August 2014, Ignatova wrote, “We are not mining actually but telling people sh*t.”

OneCoin’s value was not based on market supply and demand like other cryptocurrency, prosecutors said, but simply manipulated privately by OneCoin itself.

The facade started cracking in 2016 when investors had a hard time selling their OneCoins to recoup their original investments, court documents say.

Word began to spread online that the business was a scam. Media outlets started asking questions. International and US federal investigators got involved.

It’s not clear what happened to Ignatova’s marriage. But the FBI said she learned OneCoin was being investigated after she bugged an apartment belonging to her American boyfriend and found out he was cooperating with a federal probe into her company’s practices.

In October 2017, the US Department of Justice charged Ignatova with one count each of wire fraud, conspiracy to commit wire fraud, securities fraud, and conspiracy to commit money laundering, each of which carries a maximum sentence of 20 years in prison. She also was charged with one count of conspiracy to commit securities fraud, which carries a maximum five-year sentence. A federal judge in New York issued a warrant for her arrest.

Less than two weeks later, on October 25, 2017, she boarded a commercial flight from Sofia, Bulgaria, to Athens, Greece, court documents said.

Then she disappeared, leaving her business partners to take the fall for the failing company.

The FBI said it believes she may have traveled on a German passport from Athens, possibly to the United Arab Emirates, Germany, Russia, Eastern Europe or even back to Bulgaria. It’s offering a $100,000 reward for information leading to her arrest.

“She left with a tremendous amount of cash,” Michael Driscoll, the FBI’s assistant director-in-charge in New York, told reporters. “Money can buy a lot of friends, and I would imagine she’s taking advantage of that.”

Her partners weren’t so lucky. Greenwood was arrested in July 2018 at his home in Koh Samui, Thailand, and extradited to the US. He pleaded guilty in December to wire fraud, conspiracy to commit wire fraud and conspiracy to launder money. He is in jail and faces 20 years in prison for each of the three counts when he’s sentenced in April.

Ignatova’s brother, Konstantin Ignatov, was arrested in March 2019 at Los Angeles International Airport. He’d traveled to the US on business and was preparing to board his return flight to Bulgaria when five large men in suits handcuffed him and took him to an interrogation room, where they peppered him with questions about his missing sister, Bartlett wrote.

Ignatov pleaded guilty to wire fraud conspiracy, money laundering and fraud charges, and is scheduled to be sentenced in February.

OneCoin has shut down and its website is no longer active.

But its founder, the woman in the long gowns and flashy jewelry, has eluded authorities. More than five years after the Cryptoqueen got off a plane in Greece, her whereabouts remain a mystery.

CNN’s Allison Morrow contributed to this story.