The indictment alleged she deposited stolen funds into her personal accounts. Nirschl also withdrew the funds from ATMs at Harrah’s North Kansas City casino, the Buffalo Run casino in Miami, Okla., the Stables casino in Miami, Okla., the Downstream casino in Quapaw, Okla., Harrah’s News Orleans casino and Harrah’s Lake Tahoe casino.

The FBI investigation was launched sometime after the NCUA made an unannounced examination of Parsons Pittsburg on Jan. 14, 2014. On that day, Nirschl was questioned by an NCUA examiner about her gambling activities, according to an FBI investigator’s affidavit.

She told the examiner that during 2012, she and her husband had winnings and losses of $16 million. The FBI affidavit shows that during the month of September 2013, Nirschl made more than $500,000 in ATM transactions, electronic check transactions, ATM point of sale transactions and cash withdrawals at two casinos.

What's more, during the NCUA interview, she had a bag that was filled with 500 IRS forms that documented her gambling winnings, which totaled $4 million in December and November of 2013. It was not explained why Nirschl had the bag with her during the interview.

Although Nirschl told the NCUA examiner that she and her husband usually “break even” when they gambled, they kept $40,000 to $50,000 in cash at their home to draw on to cover their losing streaks. The source of this cash was from their gambling winnings and her and her husband's salaries.

Her husband, Jerry, was a retired postmaster of the U.S. Postal Service and worked as a handyman at a local school. His annual salary was not specified in court documents. However, according to the credit union's IRS 990 forms, Nirschl earned $61,801 in 2013. In 2014, however, she received only $3,846 in compensation, according to Parsons Pittsburg's IRS 990 form.

“The examiner asked Nirschl if she ever used credit union money to gamble with, and she replied ‘no,’” the FBI investigator wrote in the affidavit. “The examiner then asked if there were any deposits that had been made into the credit union that were not recorded properly on the credit union books, and Nirschl again replied ‘no.’”

During the interview, Nirschl told the examiner that she could produce copies of her tax returns showing that she and her husband broke even from their gambling.

But the examiner informed Nirschl she was being placed on temporary paid leave until after the examination was completed.

Even when the examination was under way and Nirschl's job was on the line, she continued to gamble. Currency transaction reports filed by casinos revealed that Nirschl inserted $192,269 into gaming devices from Jan. 20, 2014 to March 13, 2014. The CTRs also showed that Nirschl received $57,500 in cash payouts.

If the former credit union executive is convicted, she faces up to 30 years in prison for each embezzlement count, up to 10 years for each money laundering count, up to 10 years for each interstate transportation of stolen property count and up to five years for each tax evasion count.