Investigators in a House subcommittee plan to question two more top executives at MF Global in coming weeks over $1.2 billion in missing customer funds, sources close to the probe said Tuesday.

The executives allegedly have direct knowledge of $875 million in company transfers of the money.

Their identities were disclosed for the first time last week at a hearing of the House Financial Services oversight subcommittee; they now could become important new witnesses in the subcommittee’s MF Global investigation.

Among other things, the subcommittee is trying to determine who at MF Global may have authorized, legally or not, transferring customer funds out of protected, segregated accounts in the company’s commodities trading operation to other company divisions.  The Justice Department, financial regulators and the court trustee in the company’s bankruptcy proceedings have launched their own probes into the matter, as have two other Congressional committees.

The new allegations about the two MF Global executives came in a document submitted to the subcommittee by the CME Group Inc., a major commodities exchange firm based in Chicago, and provided new leads for staff investigators, sources said.

The document included a CME account--a timeline--of events and communications between officials at MF Global, the CME Group and government regulators in the week in October before the firm collapsed.

The timeline said that Christine Serwinski, the chief financial officer of MF Global’s securities trading operation, and Edith O’Brien, the operation’s treasurer, met with the CME Group’s chief auditor, Mike Procajlo, early in the morning on Oct. 31 in Chicago to disclose that $700 million of funds in segregated commodities accounts had been “moved” to the securities unit “to meet liquidity issues in a series of transactions” the week before the firm filed for bankruptcy.

But when MF Global officials told CME employees and regulators the day before that the company had confirmed a “potentially huge deficiency” in its segregated accounts, Serwinski and O’Brien told Procajlo that it “must be an accounting error…it is too big to be anything else,” the timeline said.

MF Global made its failed $6 billion bet on European debt in its securities unit, also known as a broker-dealer operation. It managed trades for the firm’s own customers but also for its own account.

The timeline said that Procajlo “was told” in the Oct. 31 meeting that the firm also had made an internal loan of $175 million to its United Kingdom operations with funds from segregated accounts, which are supposed to be managed as safe, cash customer accounts. Later that morning, MF Global filed for bankruptcy.

Subcommittee investigators now want to privately interview Serwinski and O’Brien as part of their investigation, sources said; they have already interviewed about a dozen other people involved in MF Global’s collapse, including other current and former MF Global executives, but so far have not identified who may have been responsible for moving the missing $1.2 billion. Investigators may also interview Procajlo at some point, sources said.

So far, the subcommittee has called only two MF Global figures to testify publicly: former MF Global chairman and chief executive officer Jon Corzine and MF Global chief operating officer Bradley Abelow. They were the key witnesses at last week’s hearing.

Experts say that if MF Global followed applicable rules and regulations for transferring or lending segregated customer funds internally to other company operations, the transactions could have been legal and proper.

But CME Global executive chairman Terry Duffy testified last week to a Senate committee that the CME believes the transactions were improper.

“What happened here was somebody went in, violated the rules of the CME and violated the rules of the government and transferred out customer monies into the broker-dealer account,” Duffy said.

Corzine and Duffy have been battling publicly over the CME’s account of what transpired in MF Global’s final days and Corzine’s role in them.

The CME timeline said that on the night of Oct. 31, Procajlo “participated in a phone call” with unnamed “senior” MF Global employees and that one of them “indicated that Corzine knew about loans that had been made from the customer segregated accounts.” In testimony, Duffy said the disclosure referred to the $175 million transfer to the firm’s U.K. operations.

But Corzine has said repeatedly that he does not know what happened to the missing $1.2 billion--any of it--or that he authorized any use of the funds.

Under questioning by subcommittee members last week, however, Corzine said that the CME allegation may have been referring to a large transfer of funds--he did not say how much--to a revolving credit line for MF Global in London managed by JPMorgan Chase (JPM) after the bank notified him the account was overdrawn.

“At that time, I was trying to sell billions of dollars of securities to JPMorgan Chase in order to reduce our balance sheet and generate liquidity,” Corzine said. “JPMorgan Chase told me that they would not engage in those transactions until overdrafts in London were cleaned up. I contacted (MF Global’s) back office in Chicago and others and asked them to resolve this issue, which I understood they did.”

Corzine said his MF Global contact in Chicago was O’Brien.

Corzine added, “While the last few days of MF Global were chaotic, I did not instruct anyone to lend customer funds to MF Global or any of its affiliates, nor was I told that anyone had done so.”

A spokesperson for MF Global Holdings, the parent company of the firms securities and commodities units now in bankruptcy, referred questions about Serwinski and O’Brien to the bankruptcy trustee. “They are not employees of the Holdings company,” she said.

A spokesman for the trustee said he would pass along requests for comment and interviews with Serwinski and O’Brien to them. He added that they are now “temporarily employed in assisting the Trustee in the effort to process claims and other matters for the benefit of customers…The Trustee is looking at months of transactions as part of a deliberate, thorough and independent investigation whose primary focus is what we can recover and return to customers.”

The CME Group said its timeline was based “on individuals’ best recollections and/or our ability to reconstruct events using the available documents that have been reviewed.”  You can read the document for yourself here.  It has declined to comment on its account beyond Duffy’s testimony.

Sources said the subcommittee plans additional hearings on MF Global in February, focusing on the role of credit rating agencies in the company’s failure.

Peter Barnes joined FOX Business Network (FBN) in September 2007. He serves as FBN's senior Washington correspondent.