Conversation so far:
who was the first us president that was assassinated
Abraham Lincoln was the first U.S president Assassinated.
How was Abraham Lincoln assassinated
Booth entered from behind, aimed a .44 caliber Derringer pistol at the back of Lincoln's head, and fired, mortally wounding him.
Where was Abraham Lincoln assassinated
Abraham, Lincoln was assassinated at Ford's Theatre in Washington, D.C
When was Abraham Lincoln Assassinated
The assassination of United States president Abraham Lincoln took place on Good Friday, April 14, 1865.

Question: Who was the assassin
Self-contained rewrite: Who was the assassin of President Abraham Lincoln