UPDATE 1-Lehman Brothers Holdings is focus of grand jury probes

The firm has hired restructuring company Alvarez & Marsal, which has more than 100 employees working on the case. That number is expected to swell to more than 400, Miller said, with many of the additions expected to focus on unwinding the firm's derivatives contracts.

Miller said the firm was working to unwind approximately 1.5 million derivative transactions involving about 8,000 counterparties.

Lehman has received thousands of information requests from trading counterparties, but is still working to locate and sort through data related to many of those trades, Miller said.

"In 45 to 60 days we should be in a position where we can answer specific inquiries," Miller told the court. (Additional reporting by Chelsea Emery)