A court had issued a preliminary ruling in favor of his extradition to the U.S. to face tax-related criminal charges earlier in the day.
Security personnel at the Brians 2 penitentiary near Barcelona tried to revive him, but the jail’s medical team certified his death, the Associated Press reported, citing a statement from the regional Catalan government.
"Judicial staff have been dispatched to the prison and are investigating the causes of death,” the statement said. “Everything points to death by suicide.”
The statement didn’t identify McAfee by name but said he was a 75-year-old U.S. citizen awaiting extradition to his country.
A Catalan government source familiar with the event who was not authorized to be named in media reports confirmed to the AP that the man was McAfee.
Spain’s National Court on Monday ruled in favor of extraditing McAfee. In a hearing earlier this month he had argued that the charges against him were politically motivated and that he would spend the rest of his life in prison if he was returned to the U.S.
The court’s ruling was made public on Wednesday and could be appealed. Any final extradition order would also need to get approval from the Spanish Cabinet.
Tennessee prosecutors charged McAfee with evading taxes. The charges said he failed to report income from promoting cryptocurrencies while he did consulting work, as well as income from speaking engagements and selling the rights to his life story for a documentary.
McAfee founded McAfee Associates in 1987 and ran it until 1994, when he left the company.
Since leaving McAfee Associates, he has founded a number of companies, including Tribal Voice, which offers the PowWow chat program; QuorumEx and Future Tense Central.
He was arrested last October at Barcelona’s international airport. A judge ordered at that time that McAfee should be held in jail while awaiting the outcome of a hearing on extradition.
John McAfee was a person of interest in a 2012 murder of a neighbor in Belize, though he wasn’t charged with a crime, Bloomberg reported.
The dead neighbor’s family later filed a wrongful death suit against McAfee and last year a court in Florida found against him, ordering him to pay the family more than $25 million.
Last year, he was detained in the Dominican Republic for entering the country with firearms and ammunition.
In 2016, he sought the Libertarian Party nomination for president, losing to former New Mexico Gov. Gary Johnson. He tried again last year but also came up empty.