On April 14, 1865, President Lincoln, his wife
Mary Todd Lincoln,
Major Henry Rathbone and his fiancée
Clara Harris were attending the play
Our American Cousin at
Ford's Theatre. Parker was assigned to guard the entrance to the President's box where the four were seated. He is known to have, at first, stayed at his assigned post, but he later told family members that he was then released by Lincoln until the end of the play. During the intermission, Parker went to a nearby tavern with Lincoln's valet and
coachman, got drunk and fell asleep. Parker attempted to defend himself stating that he "could never stoop to murder much less to the murder of so good and great a man as the President. I did wrong, I admit, and have bitterly repented." Mrs. Lincoln told Parker that she would always think he was responsible for the President's death and angrily dismissed him from the room. ==Later years and death==