Jack the Ripper: Case Study

Lesson 7: Using Forensic Evidence to Investigate an Old Crime

In this section we will continue an exploration of Cornwell's book by looking at the actual forensic techniques employed by author and researcher Patricia Cornwell in her attempt to prove that Walter Sicker was Jack the Ripper. The evidence will be examined and the effectiveness of the forensic techniques used will be discussed. An attempt will be made to determine whether or not her evidence was conclusive. The primary source for this lesson will be Portrait of a Killer: Jack the Ripper--Case Closed.

Forensic Evidence

In this section we will continue an exploration of Cornwell's book by looking at the actual forensic techniques employed by author and researcher Patricia Cornwell in her attempt to prove that Walter Sickert was Jack the Ripper. The evidence will be examined and the effectiveness of the forensic techniques used will be discussed. An attempt will be made to determine whether or not her evidence was conclusive. The primary source for this lesson will be Portrait of a Killer: Jack the Ripper--Case Closed.

A Search for Forensic Evidence

Patricia Cornwell first became intrigued by the Ripper case when she was invited to Scotland Yard in 2001 to do research for one of her fiction novels. She became so fascinated with the mystery of the yet unsolved Jack the Ripper murders she decided to write a nonfiction book about the case.

Her idea to apply modern forensic techniques in an attempt to solve a crime over a century old had never before been attempted. Hers was not a small project. Cornwell spent six million dollars of her own money and purchased thirty of Sickert's paintings in an effort to prove her theory that Walter Sickert was Jack the Ripper. She hired a team consisting of a handwriting expert, forensic photographer, and a DNA expert.

DNA Evidence on Ripper Correspondence

DNA testing was performed on the backs of stamps and envelopes from 250 Ripper letters, which was then compared to Sickert's own personal correspondence. DNA testing of material over 100 years old had never before been attempted. Many of the letters had been sealed under plastic in order to preserve them, which destroyed the DNA. The experts went through the Ripper letters in order to find a trace of nuclear DNA evidence, but the results were disappointing. Not a trace of human DNA was found.

One letter existed that had not been stored in plastic so DNA tests continued. Here, it gets complicated. Cornwell arranged for more sophisticated testing, this time for mitochondrial DNA.

On one letter called the "Openshaw" letter, mitochondrial DNA sequences were found that were similar to those on Sickert's correspondence. But mitochondrial DNA is not as specific as nuclear DNA. A match between two samples does not mean that one person left both, but only that a certain percentage of the population could have left both. It is estimated that the DNA sequence could match at least 33,000 other people besides Sickert.

Because the letters tested had been handled by numerous people, the DNA evidence had also been contaminated. The DNA found on the Sickert letters was a blend of several different people.

Also, since Sickert was cremated after his death and his DNA no longer exists, conclusive evidence was unobtainable. In other words, it is generally believed that the small trace of DNA evidence Cornwell's team was able to extract from the Ripper letters and Sickert's correspondence was inconclusive. In Cornwell's own words, the evidence served as a "cautious indicator" Sickert may have been involved in the Ripper crimes.

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