If the Knapps and the Crowninshields were not the conspirators in this murder, then there is a whole set of conspirators not yet discovered.  Because, independent of the testimony of Palmer and Leighton, independent of all disputed evidence, we know, from uncontroverted facts, that this murder was, and must have been, the result of concert and co-operation between two or more.  We know it was not done without plan and deliberation; we see, that whoever entered the house, to strike the blow, was favored and aided by some one who had been previously in the house, without suspicion, and who had prepared the way.  This is concert, this is co-operation, this is conspiracy.  If the Knapps and the Crowninshields, then, were not the conspirators, who were?  Joseph Knapp had a motive to desire the death of Mr. White, and that motive has been shown.

He was connected by marriage with the family of Mr. White.  His wife was the daughter of Mrs. Beckford, who was the only child of a sister of the deceased.  The deceased was more than eighty years old, and had no children.  His only heirs were nephews and nieces.  He was supposed to be possessed of a very large fortune, which would have descended, by law, to his several nephews and nieces in equal shares; or, if there was a will, then according to the will.  But as he had but two branches of heirs, the children of his brother, Henry White, and of Mrs. Beckford, each of these branches, according to the common idea, would have shared one half of his property.

This popular idea is not legally correct.  But it is common, and very probably was entertained by the parties.  According to this idea, Mrs. Beckford, on Mr. White’s death without a will, would have been entitled to one half of his ample fortune; and Joseph Knapp had married one of her three children.  There was a will, and this will gave the bulk of the property to others; and we learn from Palmer that one part of the design was to destroy the will before the murder was committed.  There had been a previous will, and that previous will was known or believed to have been more favorable than the other to the Beckford family.  So that, by destroying the last will, and destroying the life of the testator at the same time, either the first and more favorable will would be set up, or the deceased would have no will, which would be, as was supposed, still more favorable.  But the conspirators not having succeeded in obtaining and destroying the last will, though they accomplished the murder, that will being found in existence and safe, and that will bequeathing the mass of the property to others, it seemed at the time impossible for Joseph Knapp, as for any one else, indeed, but the principal devisee, to have any motive which should lead to the murder.  The key which unlocks the whole mystery is the knowledge of the intention of the conspirators to steal the will.  This is derived from Palmer, and it explains all.  It solves the whole marvel.