Answer each question. Be courteous. And don't huddle with your lawyer before replying.
He said very little. Nevertheless, it was a risky strategy, even for a risk-taking financial executive. Anything Corzine might say could be used against him in a courtroom, should he ever be charged in the MF Global case.
Yet the former CEO of the securities firm never declined to answer questions by invoking his Fifth Amendment right against self-incrimination.
The one-time senator and New Jersey governor was subpoenaed by his former colleagues to explain how MF Global collapsed just over a month ago in the eighth-largest bankruptcy in U.S. history. It's the first time in more than 100 years that Congress has subpoenaed a former senator to testify, according to Senate historian Don Ritchie.
Looking strained and speaking hoarsely during nearly three hours of testimony, Corzine said he never intended to break rules that require firms to safeguard client funds. He said he doesn't know what happened to the missing money, but added that customers' losses weigh on his mind "every day, every hour."
He said several times that he did not become aware of the shortfall in client accounts until Oct. 30, one day before MF Global filed for bankruptcy following its disastrous bets on European debt.
"I'm not in a position, given the number of transactions, to know anything specific about the movement of any specific funds," said Corzine, who took over as CEO more than a year and a half ago.
In his testimony to the House Agriculture Committee, Corzine sought to deflect blame for the company's collapse, arguing that he inherited a firm already doomed by his predecessors' bad financial decisions.
Legal experts said they were surprised by Corzine's decision to answer each question, however vaguely, given the legal risks. The FBI and federal regulators are investigating MF Global.
It's hard to see how the testimony will benefit Corzine, said Robert Mintz, a defense attorney in Newark, N.J., who specializes in white-collar cases.
Mintz said Corzine's answers leave him open to "a barrage of questions about facts and circumstances that will no doubt be the subject of review by prosecutors and regulators."
Two other congressional panels have also voted to subpoena Corzine.
His testimony provided his first public comments since the firm's spectacular collapse. A lawyer who handles white-collar criminal cases accompanied Corzine and sat behind him during the hearing. But Corzine never turned to seek his advice.
The hearing wasn't particularly confrontational, though a few members expressed disbelief that Corzine could be so detached as CEO.
Rep. David Scott, D-Ga., told him it strained belief "for you to sit there and say ... you know nothing about" the missing customer money. A lot of farmers in Georgia need to know, Scott said. "The key to this is you. You're the CEO."
Corzine said he was confident that others at MF Global were checking daily to ensure that the firm's money and clients' fund were being kept separate.
"I simply do not know where the money is, or why the accounts have not been reconciled to date," he said.
He said MF Global toppled, in part, because of a large quarterly loss caused by his predecessors' accounting moves. Rating agencies responded to the loss by downgrading the firm's credit rating, which panicked investors and trading partners.
"The marketplace lost confidence in our firm," he said. He disputed media reports that he personally pushed the company to make big, doomed bets on risky European debt using too much borrowed money.
He said he made the high-stakes bets only after discussions with company executives who traded European debt long before he arrived. And he said he reduced MF Global's investment risks in some ways.
Some outside experts challenged some of his assertions.
Janet Tavakoli, an expert on the transactions MF Global specialized in, said Corzine's remarks seemed to divert attention from the firm's fundamental flaw under his leadership: It lacked the cash to cover its bets after investors started to fear that a major European nation would default.
"His entire testimony looks like a very skilled way to try to detract from that key issue," said Tavakoli, president of Tavakoli Structured Finance.
Lawmakers have heard from farmers, ranchers and small-business owners who are missing money deposited with the firm. Agricultural businesses use brokerage firms to help reduce their risks in an industry vulnerable to swings in oil, corn and other commodity prices.
A Democrat, Corzine represented New Jersey in the Senate from 2001 through 2005. He later served a single four-year term as governor, losing a re-election bid in 2009. Before entering politics, he was CEO of Goldman Sachs.
Corzine became CEO of MF Global in March last year, succeeding Bernard Dan, who resigned. Dan, a former CEO of the Chicago Board of Trade, was later named president of Sun Holdings LLC, a Chicago-based proprietary trading firm.
Several class-action lawsuits on behalf of shareholders have been filed against Corzine and three other top executives, accusing the firm and its leaders of making false statements about MF Global's stability.
Stephen Gillers, a professor at New York University School of Law, said lawyers typically advise clients in Corzine's situation not to answer questions.
"When you answer a full day's worth of questions, you're committing yourself to a story that could come back to haunt you," Gillers said.
Mintz added: "It only makes sense if your answers can satisfy those posing the questions. Short of that, the risks far outweigh the benefits."
Samantha Bomkamp contributed to this report from New York.