Mumford did not immediately return an e-mail Tuesday asking for details.
Koerber was originally indicted on three counts in May 2009, but 19 additional charges were added in a previous superseding indictment.
Koerber charged large fees for seminars and classes about investing in real estate using procedures he called "equity milling." Prosecutors allege he lured in hundreds of investors with promises of returns of 5 percent or so a month before the companies collapsed when the nation's real estate bubble burst in 2008.
The indictments allege he used about half of the $100 million from investors to pay back initial investors and also spent funds on investments other than real estate, contrary to what he told investors their funds would go toward. Using monies from new investors to pay back earlier ones is known as a Ponzi scheme.
The second indictment was thrown into doubt when U.S. District Judge Clark Waddoups ruled that a key piece of evidence, the draft of a letter to investors, was a private document between Koerber and his attorneys, and couldn't be used as evidence in a trial. The new indictment for which he was to appear on Thursday contains 20 charges but it dropped the one related to the letter.
Koerber previously pleaded not guilty and vowed to go to trial in the case. He denies doing anything illegal.