However, Professor Alan Woodward, a cybersecurity expert at the University of Surrey, said if he was Mr Sheppard he “would be slightly worried”.
“The Americans will issue a legal aid warrant,” he said.
“In this case, they didn’t just break and enter, but then tried to use it for a criminal scam. They walked away with thousands of pounds. So you know that these were not insignificant amounts of money. I suspect that the British law enforcement will not have much sympathy with them.
According to neighbors, Mr. Sheppard – who attended a local public school – is “a nice boy” whose father, Mark, died about five years ago.
They added that her mother, Lorraine, had been raising her since her husband’s death.
A woman in her sixties, who lives on the same street, said: “I know Lorraine and she is lovely.
“I haven’t seen Mason in years, but he’s always been a very nice boy.
“It’s a real shock. No one here saw any police activity or anything.
David Anderson, the US District Attorney for the Northern District of California, said Mr. Sheppard “faces a legal maximum sentence of 45 years” if convicted.
All three charges were filed against him in the Northern District of California, where Twitter is located.
Tweets were posted simultaneously promoting a Bitcoin scam, promising subscribers that they would receive double the amount of money refunded if they transferred funds to a digital wallet.
According to court documents filed on July 23 and made public on Friday, around 415 transfers were made to the Bitcoin address for a total of over US $ 117,000, or around £ 90,000.
Nima Fazeli, 22, of Orlando, Florida, has been charged with aiding and abetting intentional access to a secure computer.
The Justice Department said charges had also been filed against a minor.
Graham Ivan Clark, 17, was arrested in Tampa, Florida on Friday, according to the Hillsborough state attorney’s office.
He added that Mr. Clark would be prosecuted as an adult and that he would be the “mastermind” behind the hack.
Mr Anderson said: “There is a false belief within the criminal hacker community that attacks like the Twitter hack can be carried out anonymously and without consequence.
“Today’s charge announcement demonstrates that the excitement of malicious hacking in a secure environment for fun or profit will be short-lived.
“Criminal conduct on the Internet may seem stealthy to those who commit it, but it is not stealthy.
“In particular, I mean to potential offenders, break the law, and we’ll find you. ”
A spokesperson for the Home Office said: “As a long-standing policy and practice, we neither confirm nor deny the existence of extradition requests.”