Fallen crypto mogul Sam Bankman-Fried "stole billion of dollars" in cash and crypto from thousands of people and lied constantly to do so, prosecutors today alleged.

In opening statements Wednesday morning at Bankman-Fried's trial, Assistant U.S. Attorney Thane Rehn told jurors that the ex-FTX CEO "knew his company didn't keep customer money safe."

He also alleged that Bankman-Fried's company was "built on lies" and that his close business partners knew what he was up to. "He spent other peoples money for himself," Rehn said.

FTX, once the most recognized brands in the crypto space, quickly and unexpectedly went bankrupt last November.

Prosecutors allege that Bankman-Fried comingled customer funds to make risky bets on Alameda Research and plundered the company.

But Bankman-Fried's defense lawyer, Mark Cohen, today told the court that "Sam acted in good faith and took reasonable business measures."

Cohen said that Bankman-Fried was a "math nerd" who did not steal but rather "loaned" FTX cash to Alameda, the crypto exchange's sister trading firm.

He added that Binance, the world's biggest crypto exchange, and its CEO, Changpeng ‘CZ’ Zhao, put an "attack" on Alameda Research via a tweet. Before FTX filed for bankruptcy last year, CZ announced he would be selling off Binance’s holdings of the exchange token, FTT. A liquidity crisis followed and FTX then filed for bankruptcy.

The two then clashed on Twitter about past business deals.

Bankman-Fried, who wined and dined politicians and celebs, was arrested a month after the company filed for bankruptcy.

He is now facing seven criminal charges and his trial is expected to last six weeks.

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