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. The justice department for the Catalan region of Spain said that Mr McAfee had been found dead in his cell. It added that pending an investigation, it was treating his death as a probable suicide. 

After selling his pioneering virus-fighting firm in 1994 and losing most of his fortune during the 2008 financial crisis, Mr McAfee led a peripatetic life that included a turn to paranoia and a string of arrests around the globe. That all culminated in his detention in Spain in 2020 after prosecutors in the US accused him of not filing tax returns for several years.

The indictment filed by the Justice Department said that McAfee had earned millions from “promoting cryptocurrencies, consulting work, speaking engagements and selling the rights to his life story for a documentary,” and had tried to avoid taxes by using cryptocurrency and channeling the money through bank accounts. He could have faced prison time, if convicted. Mr McAfee had said he had been arrested despite paying “millions of dollars in taxes” and resisted extradition.

Mr McAfee grew up in Roanoke, Virginia, the son of a road surveyor and a bank teller in an unhappy marriage. He said in press reports that his father was a severe alcoholic who beat him and his mother, and who fatally shot himself when Mr McAfee was 15.

McAfee Associates, the software company that he founded, was once a household name in computer security. He started it in 1987 in his small house in Santa Clara, California, in response to the news of a Pakistani computer virus called Brain – thought to be the first to attack personal computers. Mr McAfee had said that, at the time, it reminded him of the way his father would suddenly attack him.