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.