One of the strangest stories in American history is the fact that John Wilkes Booth attended Lincoln's second inauguration.
Lucy Lambert Hale (r), the daughter of Lincoln friend, Sen. John Hale of New Hampshire. They were supposedly secretly engaged although it is more likely that had Booth lied to her to worm his way closer to Lincoln to further his plots. When Booth died he had the pictures of five women with him, including Lucy.
Booth had wrangled a prime ticket to the inauguration from Lucy and ended up surprisingly close to the President. If the above picture is accurate in identifying him, Booth was within pistol shot range of his target. A month later, Booth was trying to recruit fellow actor Samuel Knapp Chester into the plot and told him, "What an excellent chance I had to kill the President, if I had wished, on inauguration-day."
Here is a fascinating website on all things Booth.