FTX founder Sam Bankman-Fried told jurors in his criminal trial on Friday that he didn’t commit fraud at his crypto exchange, which collapsed late last year.

Bankman-Fried addressed the New York courtroom a day after U.S. District Judge Lewis Kaplan sent jurors home early to consider whether some aspects of the defendant’s planned testimony, related to legal advice he got while running FTX, would be admissible in court.

On Friday morning, defense attorney Mark Cohen asked Bankman-Fried if he defrauded anyone.

“No, I did not,” Bankman-Fried responded.

Cohen followed by asking if he took customer funds, to which Bankman-Fried said “no.”

Bankman-Fried, 31, faces seven criminal counts, including wire fraud, securities fraud and money laundering, that could land him in prison for life if he’s convicted. Bankman-Fried, the son of two Stanford legal scholars, has pleaded not guilty in the case.

Prior to the defendant’s appearance on the stand, the four-week trial was highlighted by the testimony of multiple members of FTX’s top leadership team as well as the people who ran sister hedge fund Alameda Research. They all singled out Bankman-Fried as the mastermind of a scheme to use FTX customer money to fund everything from venture investments and a high-priced condo in the Bahamas to covering Alameda’s crypto losses.

Prosecutors walked former leaders of Bankman-Fried’s businesses through specific actions taken by their boss that resulted in clients losing billions of dollars last year. Several of the witnesses, including Bankman-Fried’s ex-girlfriend Caroline Ellison, who ran Alameda, have pleaded guilty to multiple charges and are cooperating with the government.

The judge’s decision to send the jury home on Thursday allowed Bankman-Fried and his defense team to audition their best legal material for Judge Kaplan.

He said people were excited about it, watching bitcoin, which had jumped from $1,000 to $10,000 in a two-month period. Banks and brokers weren’t involved yet and it seemed like there would probably be big demand for an arbitrage provider, he said.

“I had absolutely no idea” how cryptocurrencies worked, Bankman-Fried said. “I just knew they were things you could trade.”

The first Alameda office was in an Airbnb in Berkeley, California, he said. It was listed as a two bedroom but they used the couch in the living room as a third bed and the attic as a fourth.

He started FTX in 2019. Trading volume grew substantially on FTX from a few million dollars a day to tens of millions of dollars that year to hundreds of millions of dollars in 2020. By 2022, that number was up to $10 billion to $15 billion of dollars per day in trading volume, he said.

Bankman-Fried said Alameda was permitted to borrow from FTX, but his understanding was that the money was coming from margin trades, collateral from other margin trades or assets earning interest on the platform.

At FTX, there were no general restrictions on what could be done with funds that were borrowed as long as the company believed assets were greater than liabilities, Bankman-Fried testified.

In 2020, a routine liquidation gone wrong led to some of the special borrowing permissions at Alameda, he said. The risk engine was sagging under the weight of growth. A liquidation that should have been in the thousands of dollars was in the trillions of dollars. Alameda was suddenly underwater because of closing the position.

The incident exposed a larger concern, that the potential of an erroneous liquidation of Alameda could be disastrous for users.

Bankman-Fried said he talked to FTX’s engineering director Nishad Singh and co-founder Gary Wang, both of whom testified earlier on behalf of the prosecution. They suggested creating an alert, which would prompt the user to deposit more collateral, or a delay, Bankman-Fried said. They later implemented a feature like that, he said, adding that he learned it was the “allow negative” feature.

Bankman-Fried testified that he wasn’t aware of the amount Alameda was borrowing or its theoretical max. As long as the net asset value was positive on the exchange and the scale of borrowing was reasonable, increasing the line of credit so Alameda could keep filling orders was fine, he said. Bankman-Fried added that he now believes what Singh and Wang did was increase the line of credit.

Prosecutors also entered corroborating materials, including encrypted Signal messages and other internal documents that appear to show Bankman-Fried orchestrating the spending of FTX customer money.

The defense’s case, which consists of Bankman-Fried’s testimony along with that of two witnesses who took the stand Thursday morning, hinges largely on whether the jury believes the defendant didn’t intend to commit fraud.

On Thursday, under questioning led by Cohen, Bankman-Fried appeared to place much of the criminal blame on FTX’s chief regulatory officer, Dan Friedberg, as well as outside counsel Fenwick & West, which advised the crypto exchange. Bankman-Fried spoke about Friedberg’s active involvement in everything from the companywide auto-deletion policy on messaging apps like Signal, to the creation of Alameda’s North Dimension bank account, where billions of dollars worth of FTX customer money was funneled.

The former FTX chief also said that the hundreds of millions of dollars in personal loans to himself and other founders of the platform were structured through promissory notes drafted by his in-house legal team and discussed in concert with his general counsel and Friedberg. Having the blessing of his legal counsel was something that SBF said he “took comfort in.”

— CNBC’s Dawn Giel contributed to this report

WATCH: Sam Bankman-Fried testifying in his criminal case