MF Global Inc. brokerage customers have no assurance of a 100 percent return of assets as long as money is missing from the segregated accounts, a lawyer for trustee James Giddens will tell Congress.

James Kobak, the lawyer, said in prepared testimony for the House Agriculture Committee that the trustee’s team is engaged in “exhaustive efforts” to recover known pockets of money in U.S. depositories. Other known assets belonging to customers would take longer to bring back, since they are in the control of foreign liquidators of the defunct firm’s affiliate, he said.

Kobak is a witness in the committee’s hearing into MF Global bankruptcy being held today in Washington.

The trustee believes as much as $1.2 billion is missing, and isn’t ready to make “definitive conclusions” about what happened to it, Kobak said. The defunct company’s former chief executive officer, Jon Corzine, said in prepared testimony he doesn’t know where the money is.