Portrait of a Killer: Jack the Ripper—Case Closed () is a 2002 nonfiction book by crime novelist Patricia Cornwell that presents the theory that Walter Sickert, a German-British painter, was the 19th-century serial killer known as Jack the Ripper. Jean Overton Fuller, in her 1990 book Sickert and the Ripper Crimes, had maintained that Sickert was Jack the Ripper. Prior to that, Stephen Knight, in his 1976 book Jack the Ripper: The Final Solution, had maintained that Sickert had been forced to be an accomplice of the Ripper. Neither of these two books is mentioned in Cornwell's book. Cornwell's book was released to much controversy, especially within the British art world, where Sickert's work is admired, and also among “Ripperologists,” who dispute her research methods and conclusions. Cornwell lashed back at these critics, claiming that, if she were a man or British, her theory would have been accepted. She has also made remarks indicating that those who study the Ripper case would rather have the mystery than its solution. Theory Cornwell contends Sickert had the psychological profile of a killer. She asserts that many of his paintings and sketches follow a violently misogynistic theme. Cornwell's belief is that Sickert was unable to have normal intercourse because of botched surgery to correct a fistula on his penis. However, Cornwell provides little evidence for either the fistula or the surgery. The killings coincide with the marriage of Sickert's close friend and mentor, the famous painter James Abbott McNeill Whistler, who later distanced himself from Sickert, even suing Sickert later in life. Cornwell claims this marriage and the end of the friendship provided the spark which exacerbated his awareness of his disabilities and ignited a latent anger against the opposite sex. Departing from common belief among experts that most of the Ripper's letters were hoaxes, Cornwell writes that the letters contain specific information related to crimes, and as such are unlikely to be from anyone other than the Ripper. However, Cornwell's book does not discuss exactly which details of the Ripper's murders were made known to the general public at the time. Cornwell cites Sickert's artistic genius as useful for crafting the Ripper's letters by disguising handwriting and varying sketching styles. She also points to Sickert's paintings and sketches, some of which show women in prostrate poses that Cornwell claims are similar to victims at their crime scenes. Cornwell also had a stamp