Twitter Hacker Pleads Guilty in Florida Court

The hackers, who prosecutors said were led by Mr. Clark, initially used their access to Twitter’s internal systems to take over accounts with unusual user names like @dark and @vague, which they sold on OGUsers for thousands of dollars. But as the day of the attack wore on, the hackers changed tactics. Accounts belonging to celebrities and cryptocurrency companies tweeted messages that promised to double the money of anyone who sent Bitcoin.

But the offer was a scam. “No Bitcoin currency was returned as promised to these victims,” Darrell Dirks, a prosecutor with the Florida state attorney’s office, said during a court hearing on Tuesday.

Two other young men, Nima Fazeli and Mason Sheppard, were also arrested and faced charges related to the hack. Mr. Sheppard’s and Mr. Fazeli’s cases are in progress.

Mr. Clark, who appeared in court on Tuesday via videoconference, pleaded guilty to the 30 charges against him. In a deal with prosecutors, Mr. Clark agreed to three years in juvenile prison followed by three years of probation. He also agreed not to use computers without permission or supervision from law enforcement. If he violates the terms of the deal, he could face 10 years in adult prison.

Because Mr. Clark is classified as a youthful offender under a Florida law that offers more lenient sentencing terms to young people, he may be eligible to serve some of his sentence in a boot camp. He turned over the cryptocurrency he owned at the time of his arrest, prosecutors said, and it will be used to pay restitution to the victims of the hack. He will receive 229 days credit for time served since his arrest last year.

“He took over the accounts of famous people, but the money he stole came from regular, hard-working people. Graham Clark needs to be held accountable for that crime, and other potential scammers out there need to see the consequences,” Hillsborough’s state attorney, Andrew Warren, said in a statement. “In this case, we’ve been able to deliver those consequences while recognizing that our goal with any child, whenever possible, is to have them learn their lesson without destroying their future.”

David Weisbrod, a lawyer for Mr. Clark, declined to comment on the plea deal.