The criminal investigation unit of the United States Internal Revenue Service (IRS) has listed four crypto-related cases among the top ten of its “most prominent and high-profile investigations” in 2023.

In a Dec. 11 notice, the IRS unit said there were four significant cases in 2023 involving the seizure of cryptocurrency, fraudulent practices, money laundering and other schemes. Coming in at its third most high-profile investigation in the past year was OneCoin co-founder Karl Sebastian Greenwood, who was sentenced to 20 years in prison in September for his role in marketing and selling a fraudulent crypto asset.

Other cases included Ian Freeman, a New Hampshire resident sentenced to 8 years in prison for operating a money laundering scheme using Bitcoin kiosks and failing to pay taxes from 2016 to 2019. The government body was also behind aninvestigation of Oyster Protocolfounder Amir Elmaani, also known as “Bruno Block,” for tax evasion related to minting and selling Pearl tokens.

One of the oldest criminal cases that made the IRS list was the story of James Zhong, an individual charged with stealing BTC from the Silk Road marketplace in 2012. Zhong managed to conceal his role in the crime for roughly ten years before authorities raided his home in November 2021, finding the bulk of the crypto — worth more than $3 billion at the time — in a floor safe and a computer concealed in a popcorn tin.

In its annual report released on Dec. 4, the IRS criminal investigation unit said it had initiated more than 2,676 cases in the 2023 fiscal year, which included more than $37 billion related to tax and financial crimes. The government department has seized more than $10 billion in cryptocurrency since 2015.