Joseph J. Knapp, Jr. was afterwards tried as an accessory before the fact, and convicted.

George Crowninshield proved an alibi, and was discharged.

The execution of John Francis Knapp and Joseph J. Knapp, Jr. closed the tragedy.

If Joseph, after turning State’s evidence, had not changed his mind, neither he nor his brother, nor any of the conspirators, could have been convicted; if he had testified, and disclosed the whole truth, it would have appeared that John Francis Knapp was in Brown Street, not to render assistance to the assassin; but that Crowninshield, when he started to commit the murder, requested Frank to go home and go to bed; that Frank did go home, retire to bed, soon after arose, secretly left his father’s house, and hastened to Brown Street, to await the coming out of the assassin, in order to learn whether the deed was accomplished, and all the particulars.  If Frank had not been convicted as principal, none of the accessories could by law have been convicted.  Joseph would not have been even tried, for the government stipulated, that, if he would be a witness for the State, he should go clear.

The whole history of this occurrence is of romantic interest.  The murder itself, the corpus delicti, was strange; planned with deliberation and sagacity, and executed with firmness and vigor.  While conjecture was baffled in ascertaining either the motive or the perpetrator, it was certain that the assassin had acted upon design, and not at random.  He must have had knowledge of the house, for the window had been unfastened from within.  He had entered stealthily, threaded his way in silence through the apartments, corridors, and staircases, and coolly given the mortal blow.  To make assurance doubly sure, he inflicted many fatal stabs, “the least a death to nature,” and stayed not his hand till he had deliberately felt the pulse of his victim, to make certain that life was extinct.

It was strange that Crowninshield, the real assassin, should have been indicted and arrested on the testimony of Hatch, who was himself in prison, in a distant part of the State, at the time of the murder, and had no actual knowledge on the subject.

It was very strange that J.J.  Knapp, Jr. should have been the instrument of bringing to light the mystery of the whole murderous conspiracy; for when he received from the hand of his father the threatening letter of Palmer, consciousness of guilt so confounded his faculties, that, instead of destroying it, he stupidly handed it back and requested his father to deliver it to the Committee of Vigilance.

It was strange that the murder should have been committed on a mistake in law.  Joseph, some time previous to the murder, had made inquiry how Mr. White’s estate would be distributed in case he died without a will, and had been erroneously told that Mrs. Beckford, his mother-in-law, the sole issue and representative of a deceased sister of Mr. White, would inherit half of the estate, and that the four children and representatives of a deceased brother of Mr. White, of whom the Hon. Stephen White was one, would inherit the other half.  Joseph had privately read the will, and knew that Mr. White had bequeathed to Mrs. Beckford much less than half.