Below is a timeline of events:
Feb. 26: Trayvon Martin, a 17-year-old Florida high school student, is found shot and killed, in Sanford, Fla., a community north of Orlando.
Several eyewitnesses report to police that they heard a scuffle, then a cry for help, and then a gunshot.
According to the Sanford police report, George Zimmerman, 28, a self-appointed neighborhood watch captain, is found armed with a handgun, standing over Martin. He has a bloody nose and a wound in the back of his head.
Martin is unresponsive and pronounced dead at the scene. He has no weapons on him, only a pack of Skittles and a bottle of iced tea.
Zimmerman tells police he killed Martin in self defense. Taking him at his word, police do not arrest him, nor administer a drug or alcohol test. They also did not run a background check.
March 9: Trayvon Martin’s family demands that police release the 911 tapes or make an arrest nearly one month after Martin was killed. Police declined to comment at the time, but told ABC News the tapes would be released the following week.
March 12: ABC News uncovers questionable police conduct in the investigation of the fatal shooting of Martin, including the alleged “correction” of at least one eyewitness’ account.
Sanford Police Chief Billy Lee said there is no evidence to dispute Zimmerman’s assertion that he shot Martin out of self-defense.
March 16: Police recordings made the night Zimmerman allegedly shot and killed Martin sent the boy’s mother screaming from the room and prompted his father to declare, “He killed my son,” a family representative tells ABC News.
ABC News affiliate WFTV publishes excerpts from the 911 calls.
One of several petitions for Zimmerman’s arrest has garnered more than 250,000 signatures on a change.org site, and at one point signatures were pouring in at the rate of 10,000 an hour, according to the website.
March 18: Martin’s family asks Attorney General Eric Holder and the FBI to get involved in the investigation of their son’s death.