Dan Mallory, author of the bestselling thriller The Woman in the Window under the pseudonym AJ Finn, has admitted to lying about having brain cancer for years, after a lengthy New Yorker profile accused him of a long history of falsehoods around his professional history and health.

Mallory made headlines in 2016 when his identity as a book editor was revealed during a heated auction for his debut novel, The Woman in the Window. A film version of the thriller, about a woman with agoraphobia who begins spying on her new neighbours, is due out later this year, scripted by Pulitzer prize-winning playwright Tracy Letts and starring Amy Adams and Gary Oldman.

However, the New Yorker article by Ian Parker lays out a history of Mallory fabricating stories of illness and death, including that he had been diagnosed with brain cancer. The article claims Mallory had repeatedly said he had cancer, including in an Oxford University application, and to colleagues while working at publishing houses in both London and New York.

On Tuesday, several industry sources who asked to remain unidentified confirmed to the Guardian that Mallory had told them he had brain cancer while working at publisher Little, Brown in London between 2009 and 2012. One author published by Sphere, the crime imprint Mallory worked on, said that Mallory frequently spoke of having cancer and once told her that he had enjoyed reading one of her manuscripts multiple times, despite wearing an eyepatch due to losing sight in his eye after an operation on a brain tumour. The author said he never showed any evidence of being ill and that his “miraculous” recovery had long been a talking point among those around him.

A former colleague of Mallory’s at Little, Brown also confirmed that the author had told the office that he had brain cancer as an explanation for long periods out of the office. They began to suspect it was untrue after receiving emails from someone claiming to be Mallory’s brother Jake, detailing his illness. Mallory denied to the New Yorker that he was the author of those emails.

The New Yorker also alleges repeated instances of Mallory lying about his professional abilities, asserting during his job interview at Little, Brown that he had been an editor at US publisher Ballantine, when he had only been an assistant. Sources at Little, Brown told the Guardian that he later claimed to have received a job offer from a competitor, with Little, Brown offering him a pay increase to encourage him to stay. However, the competitor later told several figures at Little, Brown that it had never made an offer to Mallory and he was asked to leave. Mallory subsequently became vice president and executive editor of US publisher William Morrow.

In later years, Mallory reportedly told authors and employers that he had a PhD from Oxford, but the university confirmed that while he did complete his master’s degree there in 2004, Mallory never submitted a doctoral thesis.

Though the New Yorker confirmed that his parents and three siblings are all alive, it claimed Mallory had told people in publishing that his mother had died of cancer and his brother had killed himself. And in his college entrance application to start his doctorate at New College, Oxford, Mallory wrote that his entire family was dead as an explanation for his grades while completing his master’s degree. Craig Raine, former professor of English literature at New College, said that Mallory had written the essay as fact, and of having had a brain tumour in the past that “sort of cleared up”.

In a statement responding to the New Yorker article, Mallory confirmed he had never had cancer, saying he had used the illness to disguise his struggles with bipolar disorder: “It is the case that on numerous occasions in the past, I have stated, implied, or allowed others to believe that I was afflicted with a physical malady instead of a psychological one: cancer, specifically. My mother battled aggressive breast cancer starting when I was a teenager; it was the formative experience of my adolescent life, synonymous with pain and panic. I felt intensely ashamed of my psychological struggles – they were my scariest, most sensitive secret. And for 15 years, even as I worked with psychotherapists, I was utterly terrified of what people would think of me if they knew – that they’d conclude I was defective in a way that I should be able to correct, or, worse still, that they wouldn’t believe me. Dissembling seemed the easier path.”

He added that “like many afflicted with severe bipolar II disorder, I experienced crushing depressions, delusional thoughts, morbid obsessions, and memory problems. It’s been horrific, not least because, in my distress, I did or said or believed things I would never ordinarily say, or do, or believe – things of which, in many instances, I have absolutely no recollection.”

In a 2018 interview in the Observer, Mallory alluded to one such period, saying that depression had “forced him into periods of debilitating absence” while working for Sphere. However, he stated that new medication had made him well after he began working at William Morrow.