A trusted advisor to the wanted "Missing Cryptoqueen" and wanted by the FBI has vanished.
In France, 53-year-old Frank Schneider was under house arrest while he awaited extradition to the US.
But like his former boss Ruja Ignatova, he vanished before turning himself in to American authorities.
For his alleged involvement in a $4 billion (£3 point 2 billion) cryptocurrency scam, he faces up to 40 years in prison on fraud and money laundering charges.
The ankle tag-wearing Mr. Schneider had eluded his electronic surveillance, French authorities confirmed to the BBC.
His whereabouts have been a mystery for more than three weeks as of the 16 May date on the new arrest warrant issued by Nancy's Court of Appeal. .
The BBC was unable to get in touch with Mr. Schneider, his wife, or his lawyers.
He served Miss Ignatova, the mastermind behind the OneCoin cryptocurrency scam, as a troubleshooter. In 2017, she boarded a Ryanair flight from Sofia to Athens as detectives were closing in on her, never to be seen again. For information that results in her arrest, the FBI is offering a $500,000 (£400,000) reward.
In an interview with the BBC in August 2022 while under house arrest, Mr. Schneider expressed his doubts about receiving a fair trial in the US.
He stated on The Missing Cryptoqueen podcast, "I worry that I don't have access to a legal system where I can properly defend myself.
The so-called plea bargaining is a major component of the system. Because I firmly believe I'm innocent, this presents a problem for me already.
"A defendant faces extraordinary costs during a trial in the US. It will cost millions; in my case, the estimate is between five and eight million. I don't have those sums of money.
"As a result, I'm unsure of what would happen in the United States if I arrived. ".
While traveling with his family close to the Luxembourg border in April 2021, Mr. Schneider was first detained by French police. Before being released on house arrest, he was imprisoned for seven months.
While working with attorneys to fight his extradition, he conducted a number of interviews with journalists from his home in a sleepy French village.
Prior to founding his own private company, Sandstone, Luxembourgese national Mr. Schneider oversaw operations for the nation's intelligence service.
Coordinating the London-based attorneys and public relations specialists who aided in the "Cryptoqueen's" scam's extension was part of his work for her.
He is also accused of giving her secret police information, according to US prosecutors. He has denied it, but he did give the BBC sensitive police documents that he claimed she had obtained from leaked Europol meetings. They appeared to demonstrate how she evaded detectives before disappearing.
For an upcoming podcast episode and movie, the BBC spoke with Mr. Schneider once more in December 2022. He denied any notions that he had ever considered evading capture despite losing an appeal two months earlier against his extradition.
Running off doesn't solve anything. The conflict is still not over. ".
The French Prime Minister approved his extradition to the US on February 15, 2023, according to Nancy's Court of Appeal.
Following a report by Bulgarian investigative journalists, speculation has grown in recent months that Miss Ignatova may have been murdered. The Interpol-wanted Krasimir Kamenov was cited in their tweet as the story's source.
The murder of Mr. Kamenov in his Cape Town home last month prompted journalists to draw a connection between the killing and Miss Ignatova's disappearance. A US judge mandated "mental health evaluation/treatment" for Miss Ignatova's brother, who was also under house arrest, the day following the murder.
Konstanin Ignatov, who admitted guilt to his involvement in the OneCoin scam in 2019, is now working with the FBI.
