Sam Bankman-Fried, founder of the defunct FTX cryptocurrency exchange, was arrested after bail was revoked by a federal judge in New York.
Accused of attempting to influence witnesses set to testify against him in a trial starting soon.
Bankman-Fried, 31, has been under house arrest at his parents' residence in Palo Alto, California.
Judge accused him of repeatedly trying to impede witness testimony and providing papers to reporters.
Judge Kaplan revoked bail, stating Bankman-Fried had gone "up to the line" too often.
Bankman-Fried was handcuffed and sent to Brooklyn's Metropolitan Detention Center.
His lawyer plans to appeal, but Judge Kaplan will imprison him before the appeal's results.
FTX collapsed, once a leading cryptocurrency business, following a run on deposits.
He'll remain in jail while awaiting trial, starting on October 2.