I have always thought that Anderson and Swanson gave the best possible solution to this case. However, SPE and others have caused me to revise my opinion of an unequivocable acceptance of Anderson's "definitely ascertained fact".
In 1910 he [Anderson] says, "And the conclusion we came to was that he and his people were low-class Jews, for it is a remarkable fact that people of that class in the East End will not give up one of their number to Gentile justice."
If, by "for", he means "because", he has already formulated a theory.
Later, he says, "And the result proved that our diagnosis was right on every point".
In other words, when the Konsminski evidence, such as it is, comes to him, Anderson says, "I told you it was a Polish Jew all along."
So Anderson thinks,
1) It had to be a Jew because they would keep it quiet,
2) Swanson and Macnaghten have told me about a Jew suspect,
3) Ba da bing! It all fits and I was right all along!
Could this have been the case or am I being naive? I still like Anderson and Swanson but... oh well.