If Jack the Ripper was indeed one of two Polish Jews in London at the time, as most recent experts in the case assert, than the DNA left on the envelopes that the Ripper sent to police will seal more than the letter--but, perhaps, the famous--and daunting--case. Was it David Cohen? David Kosminsky? Their dna profiles would be radically different from the English suspects. And if the dna is Western European, as opposed to "Semitic," then these men will at last be exonerated. Read the article. Any fan of the case should be excited.