A report in a U.K. newspaper has cast doubts on the veracity of Raynor Winn’s bestselling memoir The Salt Path.

Winn’s book, published in the U.S. by Penguin in 2019, tells the story of a 630-mile walk that she and her husband, Moth, took after they lost their home and he was diagnosed with corticobasal degeneration (CBD), a rare, fatal disease.

In an article in the Observer, reporter Chloe Hadjimatheou writes that Raynor and Moth Winn are not the real names of the couple, whom she identifies as Sally and Tim Walker. Hadjimatheou asserts that the couple did not lose their house after a bad investment, as Winn writes in the memoir, but rather that the home was repossessed after they failed to repay a loan. Winn took out the loan, Hadjimatheou writes, to repay money that she allegedly stole from a former employer; the episode initially resulted in Winn’s arrest.

Hadjimatheou also cast doubts on Moth Winn’s CBD diagnosis, writing that she consulted with nine experts on the disease. “When the history of Moth’s condition, as set out in Winn’s books and by the couple in interviews, was described to them, they were skeptical about the length of time he has had it, his lack of acute symptoms, and his apparent ability to reverse them,” Hadjimatheou writes.

The Observer report comes just five weeks after the release of a film adaptation of The Salt Path, directed by Marianne Elliott and starring Gillian Anderson and Jason Isaacs as Raynor and Moth Winn.

The BBC reports that Raynor Winn issued a statement reading, “Today’s Observer article is highly misleading. We are taking legal advice and won’t be making any further comment at this time. The Salt Path lays bare the physical and spiritual journey Moth and I shared, an experience that transformed us completely and altered the course of our lives. This is the true story of our journey.”

The network also reports that publisher Penguin said in a statement, “Penguin undertook all the necessary pre-publication due diligence, including a contract with an author warranty about factual accuracy, and a legal read, as is standard with most works of nonfiction.”

Michael Schaub is a contributing writer.