The U.S. attorney's office in Minnesota is recuperating from several major cases and bracing for a grueling trial schedule taking shape for remainder of this year and well into 2013.

On deck is Frank Vennes, the top fund-raiser for Tom Petters' $3.65 billion Ponzi scheme; a handful of the two-dozen Native Mob gang members indicted last year on drug, weapons and racketeering charges; and Somali immigrant Mahamud Said Omar, who faces terrorism conspiracy charges.

Each case is complex in its own way, but prosecutors say white-collar cases can be the most daunting. Unraveling them often requires special expertise in computer forensics and forensic accounting. Investigators, prosecutors and defense attorneys must master special tools to manage the evidence.

More than 10 terabytes of data had to be mastered for the six-week trial of Jason "Bo" Beckman, Gerald Durand and Patrick Kiley, who were convicted in mid-June of helping Trevor Cook defraud more than 700 investors in a $194 million Ponzi scheme.

Assistant U.S. Attorney David MacLaughlin acknowledged the toll the case took in a memo last week to Chief U.S. District Judge Michael Davis. He asked for an additional month to work on the pre-sentencing reports, noting that "the prosecution team has spent considerable time recovering from the trial." Davis agreed.

That's just one case. Prosecutors expect to try several defendants connected to a Twin Cities-based identity-theft ring active in 14 states. And they continue to pursue individuals on securities-fraud charges related to the sale of Bixby Energy Systems stock. The trial of Bixby founder Bob Walker was just moved into 2013 because of its complexity.

Minnesota generally ranks in the top 10 federal districts nationwide on a per-capita basis for white-collar crime cases. Nearly a quarter of its prosecutions in 2010 and 2011 involved white-collar defendants, compared to an average of just under 10 percent for the nation.

Dan Browning • 612-673-4493