The Missing Cryptoqueen, Ruja Ignatova, is wanted by US authorities for $5m (£4m).
The FBI is seeking the 44-year-old Bulgarian-German woman who ran the $4.5bn OneCoin cryptocurrency fraud.
She had been missing since 2017 when US authorities obtained an arrest warrant and detectives started closing in.
A BBC podcast and video uncovered her ties to the Bulgarian underworld and the accused mafia leader behind her abduction and potential death three weeks ago.
But officials still seek Ms. Ignatova.
In 2022, the FBI put her to its top 10 most wanted list, promising $100,000, then increased to $250,000.
The US State Department's Transnational Organised Crime Reward Program upped that sum twenty-fold on Wednesday.
"We are offering a reward up to $5 million for information leading to the arrest and/or conviction of German national Ruja Ignatova, known as 'Cryptoqueen,' for her role in one of the largest global fraud schemes in history," Matthew Miller, a spokesperson for the US
Only one lady is targeted by the US operation.
A $5m reward is offered for information on Daniel Kinahan, the boss of one of Europe's largest drug gangs.
Similar rewards are available for information on Russian crime boss Semion Mogilevich and Honduran MS-13 leader Porky.
