Russell Edwards, an author and self-proclaimed "armchair detective," announced this weekend that he had solved the mystery of Jack the Ripper. In his new book, Naming Jack the Ripper, Edwards claims that the notorious 19th century killer was Aaron Kosminski, a Polish immigrant. Kosminski was 23 at the time of the killings and has long been suspected of being the man behind the murders. As Edwards told the Guardian, he has gathered genetic evidence linking Kosminski to the scene of one of the murders.

But as the Guardian and others point out, the case isn't exactly “definitely, categorically and absolutely” solved, as Edwards claims. The evidence hinges on a 126-year-old shawl, supposedly recovered from the scene of victim Catherine Eddowes' killing. One of the policemen on duty that night took the shawl home as a gift for his wife, but she was "horrified" by the blood-stained garment, the Guardian writes, so she stuck it in a box. It was supposedly passed down through the family (while never being washed). Seven years ago, though, the family finally decided to get rid of it, and it came up for auction, where Edwards bought it.

Edwards teamed up with Jari Louhelainen, a molecular biologist at Liverpool John Moores University, the Independent explains, to analyze the shawl for DNA traces. They collected genetic material from both Kosminski's and Eddowes' living relatives. DNA from semen and blood recovered from the shawl link both killer and victim to the crime, Edwards announced.

Others, however, are still skeptical. First, the shawl has been "openly handled by loads of people and been touched, breathed on, spat upon," Richard Cobb, who organizes Jack the Ripper conventions, told the Guardian. This means that the genetic material could be contaminated. The Independent also points out that most labs working on ancient DNA do so with blind samples—researchers don't know which samples are which—to prevent their biases from affecting results. Labs also go to great lengths to ensure those samples are not contaminated. "None of this," the Independent writes, "as far we know, has been done in this case."

Louhelainen's work hasn't been published in a peer-reviewed journal, either; if he does decided to publish the study, more can be said about the thoroughness of the analysis.

Kosminski, who died in an insane asylum, has long been on the top of the suspect list. The work announced this weekend is one more piece of evidence supporting the hypothesis that he was, indeed, Jack the Ripper—but it's not yet enough to close to case for good.