(Bloomberg News) A U.S. House investigations subcommittee ended a third hearing into the collapse of MF Global Holdings Ltd. with the same problem they had four months ago: No answers from the woman said to have the most information about what happened to $1.6 billion in missing client money.

Edith O'Brien, assistant treasurer at the firm's brokerage, invoked her constitutional right against self-incrimination yesterday at a congressional hearing, disappointing lawmakers seeking answers to questions about frantic money transfers during the company's final days in October.

"We're extremely disappointed," Randy Neugebauer, chairman of the committee, said at the meeting, before dismissing O'Brien for the rest of the two-hour panel.

Neugebauer told reporters later that lawmakers' interest focused on O'Brien after Jon S. Corzine, the former senator, governor and chief executive officer of MF Global, identified her in a December hearing as having knowledge of the transactions.

Neugebauer, a Texas Republican, said the subcommittee would move forward with its probe by questioning others and possibly recalling earlier witnesses, including Corzine.

"If we get to the point that we need further clarification, we'll call him back. We'll call Ms. O'Brien back. Nobody is really off-limits," Neugebauer told reporters.

Although O'Brien was not present for the question-and- answer period, her role in the transfers was a topic lawmakers returned to multiple times.

Frustrated Lawmakers

Lawmakers voiced frustration with the lack of information from the other witnesses: Laurie Ferber, the firm's general counsel, Christine Serwinski, the chief financial officer of the firm's North American broker-dealer, and Henri Steenkamp, the firm's chief financial officer. All three said they had been contacted by Department of Justice investigators in connection with the bankruptcy.

"Judging on your other responses since I sat down here some time ago, Ms. O'Brien's declaration of the Fifth Amendment was more helpful to the committee than any of your answers," Representative Stephen Lynch, a Massachusetts Democrat, told the executives.

Serwinski and Ferber did lay out their knowledge of the two-part transfer aimed at covering an overdraft -- a $200 million transfer from a segregated account at the firm's brokerage to a "house" account, followed by the move of $175 million from the house account to a London subsidiary's account at JPMorgan Chase & Co. Such segregated accounts may contain customer funds as well as a buffer of the firm's own cash.

Corzine's Involvement 'Unusual'

Serwinski said O'Brien and another employee had the authority to transfer funds from a segregated account. She also said that Corzine's personal involvement in the transfer would have been "unusual."

Vinay Mahajan, the firm's global treasurer who was not at the hearing, was identified by Serwinski as a second executive who had the authority to sign off on transfers. Mahajan also was identified in the House memo as informing colleagues in an Oct. 28 e-mail that an overdrawn account in London had to be "fully funded ASAP."

"Mr. Mahajan worked for only 10 weeks at MF Global and we're confident that he at all times acted appropriately," Gregory John O'Connell, Mahajan's attorney, said in a statement.

Ferber, the general counsel, testified that she sought O'Brien's assurance of the propriety of the transfer, which by Oct. 28 had drawn the interest of JPMorgan.

JPMorgan, by mid-afternoon of Oct. 28, contacted Corzine to request written confirmation that the transferred money was made up only of the firm's funds, Diane Genova, a deputy general counsel for the bank, told lawmakers.

JPMorgan's Request

"Mr. Corzine said he understood the request and would have someone in his organization review it," Genova said. The bank then "e-mailed a proposed draft letter to Mr. Corzine."

Corzine, 64, told lawmakers last year the firm's back- office staff had "explicitly" informed him that the $175 million transfer made before the bankruptcy filing was legal.

"I never gave any instruction to misuse customer funds, I never intended anyone at MF Global to misuse customer funds and I don't believe that anything I said could reasonably have been interpreted as an instruction to misuse customer funds," Corzine told lawmakers in December.

Ferber and Dennis Klejna, MF Global's deputy general counsel, gave verbal assurances over the course of two days that the funds were proper, Genova said.

Klejna to 'Cooperate'

Klejna "intends to fully cooperate with the government investigation of MF Global and feels it would be premature to respond to any press inquiries at this time," Helen Kim, Klejna's lawyer and a partner at Katten Muchin Rosenman LLP, said in an e-mail.

Ferber said she spoke with O'Brien about the transfers and was provided with copies of the transaction accounts.

"My very clear understanding was that if the compliance certificate was limited to those two transactions she would sign it," Ferber said of O'Brien.

The letter was never returned to JPMorgan, according to Genova. Serwinski, asked if she would have approved the transfer if she knew all of the information about the funds involved, said she would not have made the transaction.

Lawmakers from both parties expressed frustration with the way the three executives responded to their questions, reminding them that MF Global's clients included farmers and ranchers around the country who have lost money. Representative Steve Pearce, a New Mexico Republican, compared the witnesses to Depression-era bank robbers Bonnie Parker and Clyde Barrow.

'Plausible Deniability'

"Looks like there's been a great effort to maintain plausible deniability," said Representative Nan Hayworth, a New York Republican.

Representative Michael Capuano of Massachusetts, the top Democrat on the panel, told the executives that criticism from lawmakers is the least of their problems.

"Here's your concern: The people sitting next to you," Capuano said. "Because somebody is going to say something to the appropriate investigators to say this is the person who had final responsibility. And when that happens, there's going to be problems for those individuals."