Atzerodt was known in that neighborhood as Andrew Atwood. From Metz's he went to the house of his cousin, Hartman Richter, near the little village of Germantown, and remained there until he was arrested by Sergeant L. W. Grimmell on the night of the 20th. Richter denied that there was anybody in his house when inquired of by the Sergeant. When told by the Sergeant that he would have to search the house, he admitted that his cousin was upstairs in bed. His wife then spoke up, saying, "there were three men there for that matter." Atzerodt was brought to Washington and held as a prisoner for trial, as a party to the conspiracy. There is no doubt from the evidence presented, that he was not only a party to the conspiracy, but also that Booth had arranged with him and relied on him to assassinate the Vice-President. For this purpose he had removed him from the Pennsylvania to the Kirkwood House, where the Vice-President had rooms, and was boarding. This change had been made on the morning of the 14th, and Booth had been there during the day to see that all things were properly arranged. Atzerodt's revolver was found hidden away in his bed, loaded, capped, and ready for use. His bowie-knife also was found secreted in his bed; and yet there is no evidence that he was in his room, or even in the house during the evening or night. In his defense his counsel set up the plea, and proved it, that he was incapable of committing such a crime, being constitutionally a coward. He was a low-browed, vulgar vagabond, fond of whiskey, tobacco, and vicious company; a cowardly braggart, covering up his cowardice by a great pretense of bravery when the battle was not on; low enough in moral tone to do any wicked thing, but without physical courage to face the danger connected with what he had engaged to do. Booth had mistaken his man; but being a member of the conspiracy, he was equally guilty with Booth. _Arrest of Spangler._ On the strength of the facts incidentally presented in the foregoing narrative, Edward Spangler was taken into military custody, and held as a prisoner for trial. The capture of Herold has already been given. All of these prisoners were held in military custody, and under such precautions as would have rendered any attempt at rescue or escape the height of folly. In Booth's trunk a letter was found from Samuel Arnold to Booth, dated at Hookstown, Md., March 27th, 1865. This letter was signed simply "Sam," but was proved to be in Arnold's handwriting, and led not only to his own arrest, but also to that of his friend and fellow conspirator, Michael O'Laughlin. Arnold had evidently fallen into a hesitating frame of mind. I feel that I cannot do better than to give this letter entire. It is as follows:-- HOOKSTOWN, BALTIMORE CO., March 27, 1865.