Patricia Driscoll, the former girlfriend of NASCAR driver Kurt Busch, has resigned as executive director of the Armed Forces Foundation in the wake of allegations that she mishandled foundation money, Outside the Lines has learned.

FBI and IRS officials began investigating Driscoll and her oversight of the nonprofit, multimillion-dollar foundation following an Outside the Lines report on May 22. The report detailed a host of questionable practices during her 12-year run leading the Washington, D.C.-based entity, which has ties to multiple sports-related entities and athletes. Driscoll is also facing a federal whistleblower complaint filed by a former foundation employee. The Armed Forces Foundation is a charity that aims to help veterans in need.

Last week, the foundation's board of directors placed Driscoll on administrative leave, and it accepted her resignation on Tuesday night. A foundation spokesman declined to comment but issued a statement noting the foundation's accomplishments and thanking Driscoll for her work: "We are appreciative of Patricia's 12 years of service to our armed forces, veterans, and their families."

Driscoll could not be reached for comment, but a statement issued Wednesday through the foundation attributed to her said, "I am proud of what we achieved during my time at the Armed Forces Foundation. Especially as it pertains to PTSD [post-traumatic stress disorder] and TBI [traumatic brain injury], the foundation is saving lives by creating awareness and helping veterans find the services they need before taking tragic and drastic steps such as suicide."

The foundation has hired a series of outside lawyers in recent weeks, and it began an internal investigation and authorized an independent forensic audit -- both of which remain ongoing, the spokesman said.

Driscoll and Busch, who was described by Driscoll as a former AFF "celebrity ambassador," made headlines last year when Driscoll accused Busch of strangling her and smashing her head into a wall during an argument. Before the allegation, Busch was best known for his temper tantrums and a 2004 Sprint Cup championship; Driscoll was recognized as president of the AFF. An order of protection remains in place against Busch, but prosecutors did not pursue charges against him.

Outside the Lines reported in May and June that documents it had reviewed and obtained showed the Armed Forces Foundation had, in effect, been repeatedly used as a bank to lend money for or pay various personal expenses, including bills for a private company Driscoll owns.

Before they broke up in November, Driscoll often joined Busch at NASCAR races. AP Photo/Terry Renna

The documents revealed not only tax-paperwork discrepancies but also personal-expense questions: The foundation wrote a $15,000 check toward Driscoll's legal fees to a law firm involved in her child-custody case; it paid $6,315.22 for an infrared security camera shipped to her Maryland residence; it covered first-class airfare for her child; and it picked up the tab for personal expenses on vacations to Paris and Morocco. Alongside Driscoll's $171,027 foundation salary, documents show she received substantial bonuses for fundraising -- none of which was declared on the foundation's tax filings or audit reports reviewed by Outside the Lines.

In addition, records show that, for 17 months in a 19-month stretch in 2012-13, the foundation paid the credit card bill of Driscoll's private security business -- Frontline Defense Systems. The FDS charges totaled more than $100,000 and included massage treatments, dermatology visits and other personal medical expenses, toy store purchases and grocery bills, among others.

After the Outside the Lines reports, Charity Navigator, a website that rates nonprofit entities, withdrew its four-star evaluation of the Armed Forces Foundation and instead placed it on its donor-advisory list.

Brian Cooke, who joined the foundation as chief of staff in 2013, was named by the board as Driscoll's replacement.

Senior writer Seth Wickersham contributed to this report.