Amanda Knox, who was acquitted last year of murdering her British roommate while studying in Italy, has sold the rights to her memoir for $4 million (NZ $4.8m), The New York Times reported on Thursday.
The newspaper, citing people familiar with the negotiations, said that HarperCollins acquired the rights after a "heated auction among publishing houses that stretched for days."
The Times said several publishers had submitted bids for the book, including Crown, part of Random House; St. Martin's Press, a Macmillan unit; Simon & Schuster's Atria; and Penguin Group USA's Dutton.
Knox hired Washington attorney Robert Barnett of the law firm Williams & Connolly to negotiate the deal.
A court in Perugia, northern Italy, freed Knox and her Italian ex-boyfriend Raffaele Sollecito in October after acquitting them of the 2007 killing of British student Meredith Kercher.
Knox and Sollecito had initially been sentenced to 26 and 25 years in prison.
Italian prosecutors on Tuesday lodged an appeal against Knox's acquittal.
Knox, who returned to her home town of Seattle in the United States immediately after her acquittal, cannot be extradited back to Italy.