Sam Bankman-Fried took the stand in a New York courtroom on Thursday, as he and his defense team auditioned their best legal material for U.S. District Judge Lewis Kaplan.

The former crypto billionaire had originally been scheduled to testify before the jury, but the judge sent jurors home early to consider whether some aspects of Bankman-Fried’s planned testimony, related to legal advice he got while running FTX, would be admissible in court.

In a sort of mini-hearing within the trial, defense attorney Mark Cohen guided Bankman-Fried through a series of questions designed to showcase the defense’s strongest arguments of his innocence, including suggesting that he relied on FTX’s former chief regulatory officer and in-house attorney, Dan Friedberg, to guide some actions that the government claims are illegal.

Bankman-Fried faces seven criminal counts, including wire fraud, securities fraud and money laundering, that could land him in prison for more than 100 years if he is convicted at his trial in Manhattan federal court. Bankman-Fried, the son of two Stanford legal scholars, has pleaded not guilty in the case.

“Before the trial, I was convinced that SBF was headed to near-certain conviction on serious felony counts, and it was apparent to me that his defense team had not come up with anything that could derail that result,” said Renato Mariotti, a former prosecutor in the U.S. Justice Department’s Securities & Commodities Fraud Section and now a trial partner in Chicago with Bryan Cave Leighton Paisner.

“Nothing that has occurred during the trial has changed my view. The evidence of his guilt appears to be overwhelming,” added Mariotti.

In the last four weeks of trial, multiple members of the C-suite at crypto exchange FTX, and its sister hedge fund Alameda Research, have all singled out Bankman-Fried as the mastermind behind the scenes. Several of these witnesses have themselves pleaded guilty to multiple charges, including Bankman-Fried’s ex-girlfriend Caroline Ellison, who faces a maximum sentence of 110 years for crimes committed while she was the CEO of Alameda.

Prosecutors have also entered evidence to corroborate witness accounts, 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 is comprised of Bankman-Fried’s upcoming testimony along with that of two witnesses who both wrapped in just over an hour on Thursday morning — hinges on whether the jury believes the defendant when he takes the stand.

“He has always been convinced that he’s the smartest guy in the room and that he can talk his way out of any problem,” continued Mariotti.

“But the biggest problem with SBF’s testimony will be SBF himself. Given that the core issue will be intent to defraud, SBF should be portraying himself as clueless, inattentive, and in over his head. But for years he had portrayed himself as a visionary genius, and I don’t expect that to change on the stand,” he said.

Judge Kaplan previously ruled that Bankman-Fried’s lawyers could not make a so-called advice of counsel argument in their opening remarks since it might risk prejudicing the jury. On Thursday, Kaplan sent the jury home early to reconsider in a closed-door session whether to allow this line of testimony.

Under questioning led by Cohen, Bankman-Fried appeared to place much of the criminal blame on FTX’s chief regulatory officer, 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 company-wide 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.”

While taking the stand offers Bankman-Fried the opportunity to tell his side of the story to jurors, it also opens the door for federal prosecutors to go for the jugular in cross-examination. Following damning testimony from Bankman-Fried’s closest ex-confidantes and top deputies, defense attorneys for the FTX founder have failed to flip the narrative in cross-examining key witnesses or to undermine the most troubling allegations regarding their client.

Indeed, Bankman-Fried’s practice run on Thursday was tough to watch. While he came across as direct and credible in his direct examination, the grilling by prosecutors was aggressive and effective. At multiple points, the judge appeared exasperated by Bankman-Fried’s responses, once saying that the defendant had an “interesting way of answering questions.”

The defendant’s demeanor flipped 180 degrees when U.S. assistant attorney Danielle Sassoon began her questioning. He swiveled back and forth in his chair, nervously shook a piece of paper he held in his hands, repeatedly grabbed for his water bottle before responding, and skirted a lot of questions by saying he couldn’t recall what had happened.

Judge Kaplan interjected at one point, telling the defendant to “listen to the question and answer the question directly.”

On Friday morning, we’ll get a ruling from the judge on what’s admissible from the defense’s wish list of topics – as well as Bankman-Fried’s debut before the jury from the stand.

“Given that he appears headed for defeat, taking the stand can be a ‘Hail Mary’ of sorts,” said Mariotti.

“SBF will be hamstrung by his many prior statements, which could be used to impeach him. It will be difficult for SBF to weave his testimony around those prior statements.”

This week’s testimony is just the latest example of the defense team’s struggle to land a blow in the criminal fraud case.

Prosecutors spent four weeks of the trial walking former leaders of FTX and Alameda Research through specific actions taken by their boss that resulted in clients losing billions of dollars late last year.

In trying to poke holes in witness accounts, Bankman-Fried’s lawyers have repeatedly jumped around, unable to maintain a consistent timeline or coherent argument, while also opening the door for witnesses to offer additional testimony in furtherance of what they’d previously told the jury.

The scattershot approach is potentially troubling for Bankman-Fried, who’s counting on his defense attorneys to keep him out of prison in what could be a life sentence if convicted. The central claim the defense has been unable to knock down is that Bankman-Fried knowingly used billions of dollars in FTX customer funds to pay for his lavish lifestyle, to make political donations and, most dramatically, to cover a gaping hole in Alameda’s books following the cratering of cryptocurrency prices last year.

Cohen, a co-founder of the New York law firm Cohen & Gresser, is being joined at trial by Christian Everdell, a member of the firm’s white collar defense team. Cohen, a graduate of the University of Michigan Law School, started his firm 21 years ago and previously served as an assistant U.S. attorney for the Eastern District of New York. Everdell started at Cohen & Gresser in 2017 after almost a decade working as a prosecutor for the Southern District of New York.

— CNBC’s Dawn Giel contributed to this report.