The Sydney Morning Herald reported on Saturday that Norma Khuri did not flee Jordan after the killing in the late 1990s, as claimed in her book, Forbidden Love, but moved to the United States as a three-year-old and was living in Chicago when the events portrayed in her memoir took place.
The book is an emotive first-hand account of Khuri's friendship with Dalia, a Muslim woman with whom she opened a unisex hair salon in the Jordanian capital Amman.
It tells of how Dalia fell in love with one of her customers, a Catholic soldier called Michael, and her family's anger when they learned of the relationship.
Khuri says Dalia's enraged father stabbed his daughter to death and she fled Jordan fearing for her life.
She says she secretly wrote her book in Athens internet cafes before eventually settling in Australia, where she now lives in Queensland state.
Forbidden Love - A distressing true story of love and revenge in Jordan - has been published in 15 countries by Random House, selling 200,000 copies in Australia alone, where it won a prize for non-fiction writing.
The newspaper said an 18-month investigation revealed Khuri had spent most of her life in the United States, rather than in Jordan.
The newspaper said it had documents to prove Khuri was a US citizen, it had also interviewed her mother in Chicago and discovered she had a husband and two children unaccounted for in the book.
"She has four American siblings and a mother who are desperate to hear from her," the newspaper said. "But she has managed to conceal this double life from her publishers, her agent, lawyers in several continents, the Australian Department of Immigration and, until now, the public."
The newspaper said doubts first emerged in Jordan, where readers were puzzled by factual errors unlikely to be made by a local. There were other pointers, including Khuri's strong American accent and the fact that no one in Jordan could recall the hair salon, the killing or the author herself.
Khuri denied the allegations and stood by what she had written.
"I refute the allegations that you are making, and had I been given more ample time I would have supplied proof. I intend to do so in the future," she told the newspaper.
Random House said it was checking the newspaper's claims with Khuri, but said it should be remembered Khuri needed to conceal her true identity in order to flee Jordan.
If Khuri's story was proved a hoax, Australian authorities might revoke the temporary residence visa issued to the author who said she was unable to return to Jordan because her life was in danger.
Jordanian MP Hayat al-Masimi told Aljazeera the media had exaggerated the level of so-called honour killing in Jordan.
"The percentage of people killed under the phrase 'honour killing' are very few compared to those killed for other reasons," she said. "We can not say it is a phenomenon."
"Also, the so-called honour killing has been inflated by the media, and attributed to Jordan as if it does not exist elsewhere."
Traditionally, honour killing includes only the killing of a single female for having sex with a man, and a married woman for having sex out of wedlock.