Cornwell is pursuing a libel action after author Leslie Sachs posted comments claiming that her novel, The Last Precinct, plagiarised his book, The Virginia Ghost Murders.
Sachs had referred to the 50 year-old best-selling writer as a "neo Nazi" and "Jew hater" on his website.
A psychiatrist testifying in court for Cornwell referred to the comments as a case of "cyber-stalking".
"You can accuse me of a lot of things but hating a group of people or being a felon is beyond the pale," Cornwell told a Virginia courtroom.
Having already had one injunction filed against him, Sachs fixed stickers to the cover of his novel that read 'The book the famous Patricia Cornwell threatened to destroy'.
Cornwell said that Sachs's online postings had caused her emotional distress, damaged her reputation and made her fearful for her safety.
The author also claimed that she had been forced to increase her security by hiring two full-time bodyguards.
Sachs, whose previous books include How to Buy Your New Car for a Rock-Bottom Price, claims that he has fled to Belgium to escape the legal action.
Cornwell is seeking an extension to the injunction to stop Sachs posting his claims, and damages for her distress.
Novelist Patricia Cornwell sues cyber-stalker
By Matt Chapman on May 25, 2007 10:53AM