Patricia Cornwell says she lost a year of income because of her financial managers' negligenceA lawyer for Anchin, Block and Anchin LLP insisted the firm had acted "professionally and appropriately".
It blamed Cornwell's losses on the recent recession and on her supposedly extravagant spending habits.
Cornwell is best known for novels about heroine medical examiner Kay Scarpetta.
In a lawsuit in federal court in Massachusetts, the writer said that in 2009 she discovered her net worth was less than $13m, even though she had made an eight-figure annual income for the previous four years.
'Huge ordeal' Cornwell found out "that Anchin had borrowed on [her] behalf collectively several million dollars, comprised of mortgages for real property and a loan for the purchase of a helicopter," she argued in court documents.
Cornwell also accused her financial managers of failing to arrange temporary accommodation for her when renovation on her home took longer than expected.
The lawsuit added that because Cornwell suffered from bipolar disorder - a condition she says her business managers were aware of - the author's "ability to write is dependent upon the ability to avoid distractions".
"A quiet, uninterrupted environment, free of the distractions of managing her business and her assets, including her investments, is essential to her ability to write and to meet her deadlines," it says.
Cornwell said that as a result of the disruption she missed a book deadline for the first time in her career.
"This was very destabilising. I really lost my ability to focus and concentrate. I did not know what the book was about anymore," Cornwell said, according to the Associated Press.
In a lawsuit, Cornwell said the missed deadline cost her about $15m - a year of income - in book advances and commissions that could not be recovered.
"God bless justice," Cornwell said, upon learning of the verdict. "It's a huge relief and it's been a huge ordeal."
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