In a significant development in the investigation of the $4 billion OneCoin cryptocurrency Ponzi scheme, Irina Dilkinska, the company's Head of Legal and Compliance, has been sentenced to four years of imprisonment in the United States, marking another milestone in the legal battle against the fraudulent operation.

Dilkinska, a 42-year-old Bulgarian citizen, faced charges of wire fraud and money laundering, with each count carrying a maximum of five years of imprisonment.

Despite her plea to avoid jail time and return to Bulgaria to care for her young children, United States District Judge Edgardo Ramos imposed a sentence that reflects the severity of her actions within the scam.

"I honestly do not understand what prevented her from leaving the scheme before the point when it was brought down," Judge Ramos remarked during the sentencing.

Dilkinska's involvement in OneCoin included laundering $110 million through an entity in the Cayman Islands, under the guise of legal compliance.

This action was part of a larger operation that saw victims around the globe defrauded of over $4 billion. OneCoin, founded by Ruja Ignatova and Karl Greenwood in 2014, operated as a multi-level marketing scheme without a functioning blockchain, promising guaranteed returns to investors from a bogus cryptocurrency.

Ruja Ignatova, also known as the 'Cryptoqueen', remains at large after disappearing in October 2017. Her disappearance followed shortly after a federal warrant was issued for her arrest, prompting speculation about her fate, especially in light of the murders of several OneCoin associates in Mexico in 2020.

The sentencing of Dilkinska follows the conviction of other key figures in the OneCoin scam, including co-founder Karl Greenwood, who received a 20-year prison sentence.

Mark Scott, a lawyer who laundered $400 million for OneCoin, was also sentenced to ten years in prison earlier this year, highlighting the ongoing efforts by US prosecutors to hold those responsible for the scheme accountable.