Businessman John McAfee, creator of the McAfee anti-virus software, has been charged in the US with conspiracy to commit fraud and money laundering.
Mr McAfee and his bodyguard Jimmy Gale Watson Jr are accused of promoting cryptocurrencies to Mr McAfee's large Twitter following to inflate prices.
The currencies were then allegedly sold, making the pair $2m (£1.45m), prosecutors said.
The men have not commented on the charges.
Mr McAfee, 75, is currently being detained in Spain in relation to separate criminal charges relating to tax, which he denies. He faces possible extradition to the US.
Mr Watson was arrested in Texas on Thursday.
"Jimmy Watson is a decorated veteran and former Navy Seal. He fought for other people's rights and liberties, and he is entitled to and looks forward to his day in court to exercise some of those very rights," said his lawyer Arnold Spencer.
The strange life of John McAfee
The latest charges were filed in the Manhattan federal court in New York. The pair are accused of buying the cryptocurrency assets before promoting them on Twitter, where Mr McAfee has more than one million followers.
They would then sell the assets as soon as Mr McAfee's endorsements saw prices rise, according to the US justice department and the Commodity Futures Trading Commission.
They allegedly made a further $11m (£8m) in payments from cryptocurrency start-ups for promoting their assets on Twitter, payments which were not disclosed to investors who bought them.
That amounted to having "exploited a widely used social media platform and enthusiasm among investors in the emerging cryptocurrency market to make millions through lies and deception," federal prosecutor Audrey Strauss said.
In the separate tax evasion case - which was announced last October - Mr McAfee is accused of failing to file any tax returns from 2014 to 2018. Prosecutors also say he used other people's names to conceal his assets, including a yacht and property.
BDST: 1248 HRS, MAR 06, 2021