Senate Agriculture Chairman Debbie Stabenow (D-Mich.) today invited former MF Global Holdings Ltd. CEO Jon Corzine to testify at her panel’s Dec. 13 committee hearing on the firm’s bankruptcy.

Corzine and Stabenow served in the Senate together before the New Jersey Democrat became governor of his state in 2006, but Stabenow does not appear to be going easy on her former colleague, who’s former brokerage firm is currently under criminal investigation.

“The farmers, small business owners and others who trusted this firm are now facing tremendous hardship and may ultimately never recover all of their money,” Stabenow said in a release. “A discovery of this magnitude demonstrates yet again the need for strong oversight and protections for consumers to prevent this sort of abuse from occurring. Anyone engaged in wrongdoing in this matter must be swiftly held accountable, to help bring justice to victims and to prevent further erosion of confidence in the financial system.”

Corzine, a former head of Goldman Sachs, joined the firm in March 2010 and resigned earlier this month just as MF Global filed for bankruptcy. Corzine returned to the private sector after losing his 2009 gubernatorial re-election bid.

His firm was a leading commodities and derivatives brokerage, but its bankruptcy in late October was the eighth largest bankruptcy in U.S. history, according to the Stabenow statement. The FBI and Department of Justice recently opened criminal investigations into the MF Global bankruptcy. About $1.2 billion of unaccounted customer funds are under scrutiny in those inquiries.

MF Global customers have also been invited to testify at the Dec. 13 Agriculture hearing. The firm’s customers included many farmers, ranchers and small-business owners, according to the Agriculture Committee.

“As a result of the bankruptcy, MF Global customer accounts had been frozen and many customers still cannot access their own money,” the panel said. “It is possible that customers will never reclaim all of their money, meaning individual families could lose thousands, and in many cases tens of thousands of dollars.”

Stabenow has also scheduled a hearing Thursday at which officials from the Commodity Futures Trading Commission and the Securities and Exchange Commission will testify about their oversight of MF Global.