A British citizen who was extradited to New York from Spain last month has pleaded guilty to cyberstalking and computer hacking schemes, including the 2020 hack of social media site Twitter, the US Justice Department said.
Joseph James O'Connor was charged in both North Dakota and New York.
The North Dakota case was transferred to the US District Court for the Southern District of New York.
O'Connor pleaded guilty to charges including conspiring to commit computer intrusions, wire fraud and money laundering.
The 23-year-old, who was extradited to the United States on 26 April, will also forfeit more than $794,000 (€723,000) and pay restitution to victims, prosecutors said.
He faces a maximum of 77 years in prison at sentencing on 23 June.
"O'Connor’s criminal activities were flagrant and malicious, and his conduct impacted multiple people’s lives. He harassed, threatened, and extorted his victims, causing substantial emotional harm," Assistant Attorney General Kenneth Polite said in a statement.
Prosecutors said the schemes included gaining unauthorised access to social media accounts on Twitter in July 2020 as well as a TikTok account in August 2020.
Along with his co-conspirators, O'Connor stole at least $794,000 worth of cryptocurrency.
The July 2020 Twitter attack targeted a number of verified accounts, including those of then US presidential candidate Joe Biden and Tesla Chief Executive Elon Musk, who now owns Twitter.
The accounts of former US president Barack Obama, reality TV star Kim Kardashian, businessmen Bill Gates and Warren Buffett, Israeli Prime Minister Benjamin Netanyahu, Amazon founder Jeff Bezos, former New York mayor Michael Bloomberg and rapper Kanye West were also hit.
The alleged hacker used the accounts to solicit digital currency, prompting Twitter to prevent some verified accounts from publishing messages for several hours until security could be restored.
They also threatened to release private images and other information of those who were targeted.
O'Connor went by the online name of PlugwalkJoe.
In July 2021, Florida teenager Graham Ivan Clark, the alleged mastermind of the hacking group, was sentenced to three years in juvenile prison under a plea agreement.
Clark, who was 17 when he was charged, was sentenced to the maximum allowed under Florida's Youthful Offender Act.
