Several longtime donors who have invested thousands of dollars and hundreds of volunteer hours in Minnesota’s only certified refuge for large wildcats have withdrawn their support over suspicions of financial mismanagement.

Their distrust of money handling and staff relations at the Wildcat Sanctuary began with a Minneapolis law firm’s internal investigation this summer that raised serious questions about sanctuary accounting practices, including an alleged “commingling” of donor money with personal spending. Several departures from the board of directors, and the recent dismissal of employees and unpaid interns, fueled a wave of donor complaints.

“I’m absolutely outraged at what has taken place,” said Satia Pacotti of Burnsville, who’s logged 300 hours of volunteer work this year and donated money, food and other supplies for wildcat care at the nonprofit sanctuary. “We want donors to know the truth.”

Sanctuary board President Gail Plewacki, in a statement, denied accusations that donor money had been stolen. The sanctuary, which now houses about 100 wildcats including lions, tigers and cougars, “has understandably experienced growing pains” in the past few years and board members have adjusted policies and procedures accordingly, she said.

“This is just good business, not because anyone has been stealing from the organization,” Plewacki said. An “independent investigation” concluded in September examined the sanctuary’s financial records and found nothing amiss, she said. That audit report is part of a personnel review and by law can’t be shared publicly, she said.

The Wildcat Sanctuary reported contributions and grants totaling $611,781, and expenses of $488,223, in its most recent tax-exempt filing with the Minnesota attorney general’s office in 2011.

At least 100 donors have said they’re withholding their money, said Bruce Olson of Minneapolis, who had invested 155 hours at the sanctuary since January and thousands of dollars in sponsorships over the years. “I fought for quite a while not to believe these allegations,” he said.

Those donors want removal of the founder and executive director, Tammy Quist Thies, he said. They also want a full public accounting for all of the sanctuary’s assets and money, a new board of directors, and reinstatement of fired animal keepers, he said.

As many as 40 donors met recently to review a confidential report from the Dorsey and Whitney law firm that documented specific allegations of personal spending of donor money intended to feed the cats.

Olson, one of about 20 donors who drives a car wrapped with images of big wildcats to promote the sanctuary, said donors are “angry and I don’t see them giving any money. This is a tragedy in the works. We know it will never be the same once it washes out.”

Thies founded the Pine County sanctuary and is known in Minnesota and nationally for her efforts to end captive breeding of wildcats. She lobbied for a state law enacted in 2005 that prohibits buying and owning so-called exotic cats in Minnesota. She didn’t respond to interview requests this week.

Plewacki, however, said Thies built the sanctuary into one of the most respected in the country and, because of her leadership, the Global Federation of Animal Sanctuaries and the American Sanctuary Association have given their highest endorsements. One “big donor” to the sanctuary, Sue Schmitt, said Thursday that her faith in Thies has never wavered and she and her husband, Dan, will continue to pledge money despite the “rough patch” with other donors.

Plewacki said that the board retained Dorsey and Whitney last spring after receiving complaints from employees, but a second “special audit” commissioned by the new board and finished this fall determined “that the executive director had not been responsible for any misuse or theft of funds.”

Thies hasn’t been charged with a crime.

The current board reinstated Thies as executive director two weeks ago after several months in a fundraising role. Donors allege that she was removed from the top job because her money management and leadership skills came under hard criticism in the Dorsey and Whitney report. A former FBI agent was hired to interview employees, volunteers and interns, as well as review the sanctuary’s bank statements.

According to the law firm’s report, donor money was spent to pay for Thies’ husband’s skydiving lessons, for remodeling at her house, for personal meals and groceries, and for food for her personal pets. Thies used a sanctuary credit card to make purchases, including $1,192 in 2012 for food purchases for her personal dogs and cats, the investigation concluded.

“TWS could face a publicity crisis if the public and donors found out that donor funds have been used for Thies personal expenses instead of going to support TWS,” the report said.

Plewacki countered that the skydiving allegation resulted from a mixup with an online payment, and “a variety of small purchases” from stores “are likely for use in on-site housing for unpaid interns, the TWS office or other needs.” On any occasion when a TWS employee “accidentally” purchases a personal item with sanctuary funds, “cash payment is provided,” she said.

The Dorsey and Whitney report said Thies was asked to provide evidence of reimbursement, but she “failed to provide any documentation to rebut the allegations against her.”

State tax records show Thies was paid a salary of $37,973 in 2011.

Volunteer Myk Hamlin, who performed auditing duties when he was a manager for Ford Credit, said many of his 460 volunteer hours were spent working in the sanctuary office, and he noticed finances in disarray. In one instance, he said, he found a $6,000 discrepancy on a deposit slip.

The current board isn’t allowing volunteers to enter the sanctuary because professionals who have traveled from Colorado and Florida “do not need any unknown presence” as they work around the clock to “ensure the best care for the cats,” Plewacki said.

But volunteer coordinator Amy Richman said everybody is “equally upset because of the disruption to the cats,” and donors and volunteers want a fuller explanation of why they’re barred from the grounds.

“I don’t understand why all the secrecy,” she said. “We want answers. People have given thousands of hours of time. The organization is not just Tammy. That sanctuary is the work of a lot of people and a lot of donors. I feel they should be open about this. It’s the public that’s paying for it.”