Thomas F. Harney

[RJNorton]

Otto Eisenschiml (In The Shadow of Lincoln's Death) writes:

Three years after the assassination, he (Edwin Stanton) told some friends of his narrow escape. An unidentified man had rung his doorbell about 10 o'clock, he related, but had been frightened away by some of the Secretary's friends who were hastening from Ford's Theatre to his house with the tragic tidings. Nonetheless, their arrival would have been too late, Stanton claimed, and he also would have been murdered, had it not been for a broken doorbell. Because of it, the mysterious stranger's ring remained unanswered, and the War Minister's life was saved.

If this story be true any idea who the "unidentified man" was? Also, if true, why didn't the man simply try knocking?