Jon Corzine plans to tell a House committee that he doesn't know the location of clients' money that went missing from failed investment firm MF Global.

The former U.S. senator has been subpoenaed to explain how MF Global, which he led for about 20 months, collapsed into the eighth-largest bankruptcy in U.S. history and why an estimated $1.2 billion in client funds is unaccounted for.

In prepared testimony posted Thursday on the House Committee on Agriculture's website, Corzine apologizes to "all those affected" by MF Global's failure. The company filed for bankruptcy protection on Oct. 31. Corzine resigned on Nov. 3 and hasn't spoken publicly since.

"I simply do not know where the money is, or why the accounts have not been reconciled to date," Corzine says in the statement. He says he can't say whether there were "operational errors" at MF Global or whether banks or other companies have held onto funds that should be returned to MF Global.

Corzine, 64, also says that he will not invoke the Fifth Amendment to avoid answering the committee's questions — a move that was widely expected. Corzine warns, however, that he may not be able to answer certain question. He claims that since his resignation he hasn't had access "to the information that I would need to understand what happened," or to "reconstruct the events that occurred during the chaotic days and the last hours leading up to the bankruptcy filing."

Attempting to answer questions poses a risk for Corzine. Anything he might say could be used against him in a courtroom, should Corzine ever be charged in the case. The FBI and several federal regulators are investigating MF Global.

Lawmakers in both parties may have a lot to ask him. Some have heard from farmers, ranchers and small business owners in their districts 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. But MF Global increased risks by making big bets on European government debt — bets that proved disastrous.

In his testimony, Corzine says MF Global sought to restructure the Europe investments in a way that reduced the risk to the firm. Corzine says he "strongly advocated" the investments and takes responsibility for them.

Legal experts say Corzine could be held personally liable for misrepresenting to investors the risks the firm had taken. Other top MF Global executives also could face legal jeopardy, they say. Corzine will say Thursday that the company's board signed off on the investments and was aware of the risks involved.

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. The occasion blends the two worlds Corzine has occupied for his professional life — Wall Street and public office.

A Democrat, Corzine represented New Jersey in the Senate from 2001 through 2005. He later served as the state's governor. Before entering politics, he was CEO of Goldman Sachs from 1994 to 1999.

Several class-action lawsuits on behalf of shareholders have been filed against Corzine and three other top executives. A bankruptcy court is consolidating the suits. They accuse the firm and its leaders of making false statements about MF Global's strength and cash balances.

Corzine is expected to give the remarks starting at 9:30 a.m. Eastern time.