Cornwell also read extensively about Sickert's life and works. In a memoir written by one of his fans, she read that he kept a red handkerchief in his studio while he was painting the Camden series, using it for inspiration. Cornwell believes the red handkerchief was the same one that a witness saw a man hand to Kelly shortly before she was killed.
The author also found that Sickert had a psychological profile similar to that of many serial killers. He grew up with an abusive father, and was a fearful and compulsive child who washed his hands constantly.
Forensic profilers have found that serial killers often have a growing rage stemming from a painful event in early childhood. Cornwell knew that Sickert had undergone painful surgery several times as a small child, for a fistula, or abnormal canal, somewhere on his body. She later learned from Sickert's great-nephew that the fistula was on the painter's penis, meaning that the operations might have left him sterile.
Sickert married three times but never had children, and Cornwell thinks he might have had a sexual disability that set off a murderous rampage in 1888, when he was 28. "You've got this severe sexual dysfunction, and I think that was a huge trigger for him," she said.
Hunting for a Speck of DNA
With powerful circumstantial evidence linking Sickert to the Ripper's crimes, Cornwell was sure that he was the culprit. But she knew she would need physical evidence to convince people. She thought she knew how she could get it: If she could obtain DNA from letters believed to have been sent by the Ripper, she could compare them with letters known to have been written by Sickert.
The 1888 murders had transfixed all of London, and the police had received hundreds of letters claiming to be from the murderer, most of which were hoaxes. There are a few Ripper letters that are generally believed to be written by the murderer himself. The British government gave Cornwell permission to test the letters, which are kept at the Public Record Office in London.
At her own expense, Cornwell flew a whole team over to Britain: a handwriting expert, a forensic photographer to make a high-resolution record of the letters, and a DNA analyst. They discovered that the letters had been heat-sealed under plastic to preserve them, a process that degrades DNA. None of the letters had any trace of DNA.
There was renewed hope when a former Scotland Yard curator discovered a suspected Ripper letter that had never been turned over to the archive and thus had not been heat-sealed. An initial test found the letter had no trace of DNA, but the letter did have something no one had ever seen on a Ripper letter before: a watermark from Perry & Sons, an exclusive stationer of the day.
In the Sickert archives, Cornwell found that the artist had used the same stationery at the time of the 1888 Ripper crimes. Acknowledging that a defense attorney could argue that someone else wrote the letter or that Sickert wrote it as a hoax, Cornwell believes it would have been enough at the time. "The heck with defense attorneys. A jury back then would have said, 'Hang him.' "
Cornwell's team also tore apart several of her Sickert paintings, scrutinizing the frames and canvas for fingerprints or traces of blood, but found nothing. It was the same story with his painting table.
Second Test Finds DNA on Ripper Letter