The FBI's investigation into ticket fraud by a former University of Minnesota employee is focused on an alleged "sophisticated scheme," Gophers athletic director Mark Coyle said Friday. The scheme involved football and men's hockey and basketball ticket records over a six-year period.

Former Gophers ticket operations manager Brent Holck, who held his position at the university since 2008, was fired in February after the university's office of internal audit discovered discrepancies in ticket transaction records.

Coyle said the audit showed the scheme dated back to 2011. It focused on tickets that were distributed and used despite being reported as unused and not paid for. Coyle said he believed Holck acted alone.

"It is my understanding that [the FBI] investigation is ongoing," Coyle said in a statement. "It's important to note, this activity did not have any direct financial impact on fans. No fan lost a single dollar as a result of this activity."

Holck's wife, Jessica, is not under investigation, a university official said. She remains director of events for the Golden Gophers Fund.

Coyle said the fraud case was referred to an outside entity because further investigation was beyond the university auditor's capability. The FBI's Minneapolis office received the request partly because of its ability to do digital forensics.

An FBI spokesman on Friday confirmed that the bureau is aware of the audit but could not comment on the presence of any open investigation into the matter.

The spokesman said it is not unusual for the FBI to receive requests from citizens, public institutions or other organizations that suspect that they have been the victims of a fraud. The FBI works with the U.S. attorney's office on deciding whether to open an investigation, often operating on a threshold of how much money is alleged to be lost, the sophistication of the scheme and number of victims.

The timetable on the FBI's investigation is uncertain.

Staff writer Stephen Montemayor contributed to this report.

Marcus Fuller • 612-673-7570