Jack the Ripper is perhaps the most iconic serial killer in history. Part of the mystique of this dark figure is the fact that he was never identified, leaving room for endless sleuthing and speculation. Every Ripper fan has their list of favorite suspects, usually filled with famous and powerful people of the time to add even more interest. My favorite, of course, is that he was a time-traveling friend of H. G. Wells.

Now a private researcher, Russell Edwards, claims that he has finally solved the case. First I will present his story without comment, and then we can take a skeptical look at it.

Edwards claims he acquired a blood-stained shawl in 2007 that is supposed to be from Catherine Eddowes, one of the five fairly accepted victims of the Ripper. The shawl was apparently recovered from the scene of Eddowes murder, and was covered in her blood. Acting Sergeant Amos Simpson took the shawl home as a gift for his wife. She was, apparently, not impressed and stored the shawl away without cleaning it.

The shawl remained in the possession of his family until they auctioned it off in 2007 and Edwards acquired it.

Edwards then solicited the help of Dr. Jari Louhelainen, a Finnish expert in historic DNA. Louhelainen found that the 126 year old shawl contained a great deal of blood, likely all from the victim. However, he also found a semen stain on the shawl. Genomic DNA is unlikely to have survived 126 years sufficiently intact for DNA matching. However, mitochondrial DNA is more hardy and likely did survive.

Sperm, however, contain few mitochondria (almost none). Fortunately, Louhelainen was able to isolate an epithelial cell from the region of the semen stain. Epithelial cells line many tissues, and so it is possible that the cell (which would contain mitochondrial DNA) was from the same source as the semen itself.

Louhelainen was able to extract and amplify the DNA, and then type it, finding that it belonged to the haplotype T1a1. This is a predominantly Eurasian mitochondrial haplotype, fairly rare in England and more common in northern Europe.

Mitochondria are passed down almost exclusively through the female line. Louhelainen had a Ripper suspect in mind – a “Polish madman” by the name of Aaron Kosminski. He was 23 at the time of the murders in 1888 and living in Whitechapel where they took place. About 3 years after the last known Ripper murder he was placed in an asylum, and he spent the rest of his life in asylums until he died at 53.

Kosminski has always been a suspect in the Ripper murders, although perhaps one of the less romantic ones. Louhelainen actually located a living female relative of Kosminski and found that she had the same mitochondrial haplotype as the sample from the semen stain on the shawl – a 100% match, according to Louhelainen.

Edwards and Louhelainen claim that this evidence ties Kosminski to Eddowes and her murder, and that therefore he is Jack the Ripper.

But wait…

The investigation of the shawl is certainly interesting, but it is unlikely to end debate over the identity of the Ripper. Here are the many problems that have already been pointed out by critics:

The provenance of the shawl is in doubt. It is, at the very least, an odd story that a police officer would gift his wife a bloody shawl from the scene of a gruesome murder. The bloody shawl was then passed down through the family and never washed.

Even if genuine, the shawl is problematic as evidence. It has been handled by many people over the years and is likely contaminated with many sources of DNA. Even at the time it was in the possession of Eddowes it likely was exposed to many sources of DNA. It’s even possible that Kosminski, who was known to frequent prostitutes in the area, contributed to the contamination even though he did not murder her.

Louhelainen’s analysis also has problems. He has not yet published his results in a peer-reviewed journal, so there are many details about the analysis we do not currently know. However, it does not appear that he tested alternate suspects as controls. It also does not appear that the analysis was performed with blinded samples, which is standard procedure in such cases.

Further, the mitochondrial DNA haplotype match does not point to a specific person, just an ethnic group. The match, therefore, can be a coincidence.

Conclusion

The mitochondrial DNA analysis of the samples from the shawl is certainly interesting science – it is cool that scientists can isolate DNA from such an old sample, amplify it millions of times, and then sequence it. No one at the time could have imagined such technology and that it would be able to finger a suspect.

The specific story of the Eddowes shawl and Kosminski, however, is problematic. Edwards and Louhelainen may have solved the case, but it is premature to conclude that they have. Science also operates by considering every possible problem with a line of evidence, and every possible alternate explanation.

Edwards and Louhelainen will have to deal with all of these (quite reasonable) objections to their conclusions before it is likely that their claims will be generally accepted. At the very least we should have independent replication with blinded samples and adequate controls.

Perhaps the greatest barrier that Edwards and Louhelainen face to the acceptance of their claims, however, is the fact that the Jack the Ripper story is much more compelling as an enduring mystery. If the mystery is solved, and the answer is unsurprising and mundane, that takes some of the wind out of the sails of this iconic narrative.