John David McAfee, the founder of the antivirus software maker bearing his name, died in a prison in Spain on Wednesday, after a Spanish court said that he could be extradited to the United States on tax-evasion charges.
His death was confirmed by his lawyers. He was 75.
Mr. McAfee was arrested in Spain in 2020 after prosecutors in the United States accused him of not filing tax returns from 2014 to 2018, even as he earned millions from “promoting cryptocurrencies, consulting work, speaking engagements and selling the rights to his life story for a documentary,” according to an indictment filed by the Justice Department last year.
In addition, the Securities and Exchange Commission charged Mr. McAfee in October with promoting initial coin offerings — deals for cryptocurrencies — on Twitter without disclosing that he had been paid to do so. In its complaint, the S.E.C. said Mr. McAfee had pretended to be independent and impartial but had received more than $23 million for stirring up interest in the offerings.
Mr. McAfee said he had been arrested despite paying “millions of dollars in taxes” and resisted extradition, claiming he faced political persecution for denouncing corruption in the Internal Revenue Service and opposing the fiat money system, in which central banks like the Federal Reserve control the money supply. But on Wednesday, the Spanish court said it would allow the Justice Department’s request to extradite him, saying there was “no supporting evidence that such a thing could be happening.”
“The social, economic or any other relevance the defense claims the appellant possesses does not grant him any immunity,” the ruling stated.
“When I heard of John’s impending extradition, my team was fully prepared to fight for his innocence before the United States courts,” said Andrew B. Gordon, one of Mr. McAfee’s lawyers. “We knew he would appreciate the opportunity to share his story and put the false charges against him to rest. Only hours later, we were shocked to learn of his untimely death.”
The justice department for the Catalan region of Spain said that, pending an investigation, it was treating his death as a probable suicide.
Previously, Mr. McAfee was at the center of a media frenzy surrounding the death of a neighbor in Belize. In 2012, he fled his home there after the police called him a “person of interest.” The government of Belize also accused him of assembling a militia and dealing in the narcotics trade, according to media reports at the time. Within a few weeks, Mr. McAfee was arrested on charges of illegally entering Guatemala, where he had sought political asylum.
In 2016, he was back in the United States and ran for president as a Libertarian, with his campaign video declaring, “Here’s to the crazy ones.”
McAfee Associates, the software company that he founded, was once a household name in computer security. He started it in his small house in Santa Clara, Calif., in response to a Pakistani computer virus called Brain, thought to be the first to attack personal computers. His plan was to create an antivirus program and give it away on computer bulletin boards, with the hope that users would install it on their computers at work. They did, and the companies paid licensing fees, giving Mr. McAfee revenues of about $5 million a year by 1990.
McAfee Associates went public in 1992, making its founder’s stock worth $80 million, but he resigned in 1994. The company’s rise to prominence continued without him. Intel, the computer chip maker, bought the company in 2010 for $7.7 billion, then sold its majority stake to an investment firm six years later.
By that time, Mr. McAfee had lost a fortune in the financial crisis of 2008 and had moved to Central America, seeking a simpler and cheaper life, he told reporters.
Before and after McAfee Associates was bought by Intel, the company tried to distance itself from Mr. McAfee. Before it sold the company, Intel tried to rebrand it as Intel Security. But it never shook its attachment to its founder and the brand he helped create, and the name McAfee was restored when it was sold.
In 2016, when Mr. McAfee tried to use the name with a new security company, Intel filed a lawsuit seeking to prevent him from doing so. Intel and Mr. McAfee settled the lawsuit, with Mr. McAfee agreeing not to use his name in the field of cybersecurity.
Cade Metz and Raphael Minder contributed reporting.