The Trayvon Martin case began Feb. 26 when George Zimmerman, a neighborhood watch volunteer shot and killed Martin, who was unarmed. He told Sanford Fla. police that he shot in self-defense. March 16: Portions of Zimmerman's 911 call become public and Martin's parents demand an arrest. March 19: The Justice Department announces it has launched an investigation. March 21: Hundreds of protesters participate in a "Million Hoodie March" in New York. March 22: Sanford Police Chief Bill Lee announces he will step aside "temporarily" amid accusations he mishandled the investigation. March 23: Obama says if he had a son "he would look like Trayvon." March 24: The head of the New Black Panther Party announces a $10,000 bounty for the capture of Zimmerman. April 10: Zimmerman's lawyers quit because they can no longer get in touch with him. April 11: Special prosecutor Angela Corey says Zimmerman will be charged with second degree murder. His new attorney Mark O'Mara said Zimmerman will plead not guilty.