At the Abraham Lincoln Presidential Library and Museum in Illinois, an iconic stovepipe hat has become a symbol in a fierce public relations effort to save an expansive collection of Lincoln artifacts.

But the question looms large: Was the stovepipe hat even Lincoln’s?

A private nonprofit that owns the $25 million collection, including the hat, is so deep in debt that it is considering selling some of the artifacts.

The group’s chief executive has warned that the hat, size 7⅛ and made of felted beaver fur, was moving “ever closer to the auction block,” along with other items, like Lincoln’s bloodstained gloves from the night of his assassination.

The foundation paid $6.5 million for the hat in 2007 as part of a larger purchase of Lincoln artifacts.

Over the past five years, the nonprofit, the Abraham Lincoln Presidential Library Foundation, has commissioned studies by the FBI and independent historians to determine whether the hat genuinely belonged to Lincoln.

The reports concluded that the evidence of Lincoln’s ownership was uncertain, but the results were never communicated to the public. A radio station in Chicago, WBEZ, first reported on the undisclosed findings.

Current and past leaders at the museum in Springfield, Illinois, which displays part of the 1,400-piece collection, have said doubts about the provenance of the hat were never impressed upon them. However, the hat’s origin has been clouded since at least 2012, when The Chicago Sun-Times called it into question.

The first report, written by two outside museum authorities in 2013, found the documentation associated with the hat was “insufficient to claim” that it had belonged to Lincoln.

Lincoln supposedly gave the hat to a farmer from southern Illinois, William Waller, according to the report, which was provided to the New York Times by the foundation.

While some accounts say the hat was given to Waller at a debate between Lincoln and Sen. Stephen Douglas in 1858, an affidavit from a member of the Waller family in 1958 said the farmer received the hat in Washington, D.C., the report said.

The report noted that the family’s claims of authenticity were not enough. The museum, the authors suggested, “might want to soften its claim about the hat.”

The museum didn’t.

Alan Lowe, the executive director of the museum, said that is because he first saw the report last month, when one of the authors e-mailed it to him. Lowe, who became the director in July 2016, said he was shocked no one had warned him about the hat’s questionable origin.

“I was assured everyone thought it was real,” Lowe said. “I became that guy, saying, ‘I think that hat is real. I think it’s authentic.’ ”

In 2015, the foundation took further steps to gain evidence that Lincoln owned the hat, said Nick Kalm, a vice chairman of the foundation’s board of directors. It arranged for the FBI to take DNA samples from the hat, one of three of Lincoln’s believed to have survived, to see if it matched.

According to the 2017 FBI report, the analysis was inconclusive. The only DNA found appeared to be from someone who had handled the hat in modern times.

The FBI report did offer some evidence in favor of the hat’s connection to Lincoln: It is Lincoln’s size and has a stretched band, which aligns with the 16th president’s habit of storing papers there.

Lowe said he had no knowledge of this analysis until the chief executive of the foundation, Carla Knorowski, told him about it in January, when the nonprofit was seeking state funding to alleviate its debt.

The debt stems from the foundation’s purchase in 2007 of the 1,400-piece collection that included the hat. It borrowed $23 million to pay for the collection; more than a decade later, it owes more than $9 million.

The foundation’s staff began an online fundraiser in May, which has garnered only a small fraction of the funds needed before the loan must be paid in full by October 2019.

Kalm disputed that the foundation had been secretive about the reports and said Lowe and previous leaders were kept informed.

Eileen Mackevich, the museum director before Lowe, said she was not privy to either report but had heard of vague plans to perform the DNA analysis. She said she was unaware that FBI agents had traveled to Springfield twice in 2015 to take samples.

A spokeswoman for the FBI said it sometimes takes on cases like this because they can help improve the bureau’s ability to analyze degraded DNA samples, like those its analysts would encounter at a crime scene.

The differing accounts of who knew what and when reveal a vast gulf between the state-operated museum and library and the private nonprofit that owns the collections.

Kalm said he viewed the palace intrigue over the hat as a distraction from the foundation’s larger financial problem.

While the foundation made the stovepipe the centerpiece of its fundraising appeal, Kalm acknowledged that the nonprofit was not fully transparent with the public about the contents of the reports.

“Did we keep it from the public? Sure,” he said. “But this isn’t a public issue.”

The private foundation, Kalm said, had no “duty to disclose.” He said if the reports had offered conclusive evidence one way or another, the foundation would have communicated that to the public.

Lowe, the museum’s director, said the hat will not be on display until the staff looks deeper into documentation of its provenance.

Because Lincoln is such a revered historical figure, the public deserves full transparency about his possessions, said Frank J. Williams, a prominent collector of Lincoln artifacts and a former chief justice of Rhode Island’s Supreme Court.

Williams said he worried that a controversy over an alleged Lincoln artifact could raise questions about the authenticity of other Civil War-era relics.

“When you get questions like this, you really worry,” he said. “You get suspicious and concerned about the other treasures.”