After a Spanish court granted a request to have him extradited to the US, John McAfee was found dead in a Barcelona prison cell on Wednesday. Prison security tried and failed to revive the 75-year-old, who the Catalan Justice Department said appears to have taken his own life. Details of McAfee's passing are still emerging.

McAfee is one of Silicon Valley's most well-known pioneers, a driving force in now-ubiquitous antivirus technology. However, his later life came to be dominated by legal troubles and headline-grabbing personal exploits. 

What did John McAfee create? 

You're probably familiar with the name "McAfee," even if you never heard of John McAfee the person. McAfee is one of the most widely used antivirus software providers for Windows PCs and is credited as a pioneering cybersecurity company. Much of that is due to John McAfee himself, who propelled the company to prominence in 1987 by developing code protecting computers from the Brain virus -- the first computer virus created for IBM PCs. 

"When I first read about the Pakistani Brain virus, I'd never heard of a virus before, neither had anyone in technology," McAfee told the BBC in 2013. "It fascinated me."  

His company, McAfee Associates, was created in 1987 with the hopes of tapping into the burgeoning field of antivirus technology. And it did exactly that, but without its founder. McAfee sold his stake in the company in 1994, reportedly for $100 million -- though his fortune fell to around $4 million following the 2007 financial crisis.

McAfee was bought out by Intel for $7.6 billion in 2010. When Intel rebranded McAfee as Intel Security, McAfee responded: "I am now everlastingly grateful to Intel for freeing me from this terrible association with the worst software on the planet." Intel ultimately rerebranded Intel Security as McAfee in 2016.

What did he do after leaving McAfee?

After leaving the company that bears his name in 1994, McAfee embarked on a series of mostly short-lived business ventures, including a Windows-based instant messaging app called PowWow. 

By 2008, McAfee's attention had shifted from computer viruses to actual viruses. He moved to Central American country of Belize to create herb-based antibiotics he said could stop quorum sensing, the mechanism by which bacteria communicate with each other. His plant was raided in 2012 by Belize's Gang Suppression Unit, which accused McAfee of producing methamphetamine. His dog was shot during the incident, and his passport and weapons seized. After a brief detainment, he was released without charge. McAfee said the raid was in response to his speaking out against corruption in the country. 

"I was there for a year and the local politician sent a representative and asked for $2 million for a campaign donation," he told the BBC. "I said no. Two weeks later they raided my compound."

Later that year, he became a "person of interest" in the murder of his neighbor Gregory Faull, who was found dead in his home after being shot in the head. McAfee was ordered to pay $25 million under a wrongful death suit by a Florida court in 2019.

"I thought maybe [whoever it was who shot Faull] were coming for me. They mistook him for me," McAfee told Wired at the time. "They got the wrong house. He's dead. They killed him. It spooked me out." 

McAfee fled Belize into neighboring Guatemala following Faull's murder, saying he was concerned its government wanted to assassinate him. He was detained by authorities there but suffered two heart attacks before he could be sent back to Belize. He later admitted the heart attacks were "a ruse" intended to encourage authorities to send him back to the US. He was flown back to Miami in December 2012. 

And then he ran for president

McAfee ran for US president in both 2016 and 2020. 

He announced his candidacy for the 2016 race in September 2015, at first saying he'd start a new party, the Cyber Party. Months later, he changed tact and attempted to win the Libertarian Party's nomination, advocating among other things a revamping of the US' cybersecurity system. He ultimately came in third, losing to Gary Johnson. 

McAfee ran again in 2020, this time running on platform serving "the crypto community," but he dropped out of the race in March 2020.

Why was he in a Spanish prison? 

McAfee's pro-cryptocurrency platform is part of the reason he ran into legal troubles in the US. McAfee was arrested in Spain in October 2020, wanted by the Department of Justice for tax evasion. A day later, he was charged by the Securities Exchange Commission with with securities fraud.

In the years following his return to the US, McAfee became a prominent tech pundit and cryptocurrency proponent. The SEC says he made $23 million between November 2017 and Feb. 18, 2021, from promoting cryptocurrencies to his Twitter followers without disclosing he had been paid to advertise them. He was also accused of partaking in "pump and dump" schemes -- buying large amounts of little-known, cheap cryptocurrencies, promoting them on Twitter and then selling them for a huge profit. 

"The defendants allegedly used McAfee's Twitter account to publish messages to hundreds of thousands of his Twitter followers touting various cryptocurrencies through false and misleading statements to conceal their true, self-interested motives," acting U.S. Attorney Audrey Strauss said in March.  

As for tax evasion, an indictment alleged that McAfee raked in millions of dollars from speaking engagements, consulting and cryptocurrency promotion but failed to file tax returns between 2014 and 2018.

McAfee faced 30 years in prison if convicted of all the charges, and on Wednesday, hours before he was found dead, it was announced he'd be extradited to the US to face charges. 

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