CNN's Soledad O'Brien leads a special town hall event about the killing of 17-year-old Trayvon Martin, which has sparked a national dialogue on race and what it says about America. Tune in for "Beyond Trayvon: Race and Justice in America" at 8 p.m. ET Friday on CNN. And join the conversation in a live blog of the broadcast, also starting at 8 Friday, on CNN's In America blog.
(CNN) -- Here's a look at the timeline of events in the shooting of Trayvon Martin in Sanford, Florida, and the ensuing uproar.
About 7 p.m.: George Zimmerman, a 28-year-old neighborhood watch captain, calls 911 to report "a suspicious person" in the gated community called the Retreat at Twin Lakes. Zimmerman says he is following Martin after the teen had started to run, after which the dispatcher tells him, "We don't need you to do that." Zimmerman pursues Martin anyway, before losing sight of him.
About 7:10 p.m.: Phone records show Martin was on the phone with his girlfriend around the time he spotted Zimmerman while returning from a convenience store to his father's fiancée's home.
At a March 20 news conference, Martin family attorney Benjamin Crump says the girl hears someone ask Martin what he was doing and Martin asking why the person was following him. The girl gets the impression that there is an altercation in which the earpiece falls out of Martin's ear and the connection goes dead, according to Crump.
According to an Orlando Sentinel story later confirmed by Sanford police, Zimmerman tells authorities that after briefly losing track of Martin, the teen approached him. After exchanging words, Zimmerman says, he reached for his cell phone, and then Martin punched him in the nose. Zimmerman says Martin pinned him to the ground and began slamming his head into a sidewalk.
About 7:25 p.m.: Martin is shot and killed. The weather is rainy.
At the time of his death, the teenager is unarmed and carrying a small amount of cash, a bag of Skittles candy and an iced tea.
Several neighbors of the gated community called about the incident, with authorities eventually releasing the contents of seven such 911 calls. In one, a man whispers, "Hurry, please. ... There's someone screaming outside. There's a gunshot. Hurry up. ... There's someone screaming. I just heard a gunshot."
Another neighbor says, "There were gunshots right outside my house. There's someone screaming. I just heard a guy shot. Hurry up, they are right outside my house."
In another call, a woman begs the dispatchers to send help, saying someone is "screaming and hollering" for help. Moments later, she describes a light at the scene of the shooting. "Oh, my God," she says. "There's still somebody out there walking with a flashlight."
About 7:30 p.m.: Zimmerman tells police he shot Martin in self-defense. In a police report, Officer Timothy Smith writes that Zimmerman is bleeding from the nose and back of the head.
March 8: Trayvon Martin's father, Tracy Martin, family members and attorneys hold a news conference calling attention to the case.
March 13: Sanford Police Chief Bill Lee says Zimmerman has not been charged because there are no grounds to disprove his story of the events.
March 14: CNN's David Mattingly reports that police have concluded their investigation and turned the file over to the state attorney, who would have to decide on charges. Martin's parents, Tracy Martin and Sybrina Fulton, create a petition on the website Change.org calling for Zimmerman's arrest. Within a week, it is the second most-popular petition in the website's history with 877,110 signatures. The NAACP asks the Justice Department to get involved in the investigation.
March 15: In a letter to the Orlando Sentinel, George Zimmerman's father writes that his son has been unfairly portrayed as a racist. Robert Zimmerman writes that his son is Hispanic and grew up in a multiracial family.
March 16: Authorities release seven calls to police from the night of the shooting. In one of the 911 recordings, Zimmerman follows Martin. Also in one of the recordings, a voice screams "Help, help!" in the background, followed by the sound of a gunshot.
March 19: The Justice Department announces that it has launched an investigation into Martin's death. Florida Gov. Rick Scott asks state officials to assist in the investigation.
March 20: Florida Rep. Dennis Baxley, who sponsored the "stand your ground" law in 2005, says nothing in it allows people to "pursue and confront." The law allows people to use deadly force to defend themselves anywhere they feel a reasonable fear of death or serious injury. The Justice Department sends representation to Sanford to investigate and "to address tension in the community."
March 21: CNN analyzes one of the tapes of Zimmerman's call to dispatch in which he is purported to have used a racial slur. The results are inconclusive.
March 22: Lee announces that he will step down temporarily as head of the department, which has been criticized for its handling of the fatal shooting. Scott announces that he is appointing State's Attorney Angela Corey of the 4th Judicial Circuit as special prosecutor, replacing Norman Wolfinger. As the petition calling for Zimmerman's arrest reaches 1 million signatures, according to Change.org, civil rights activists, politicos, family and supporters converge on Fort Mellon Park in Sanford to rally for swift judicial action, including Zimmerman's arrest.
March 23: President Barack Obama speaks publicly for the first time on the growing controversy, saying the incident requires national "soul-searching."
Saturday: A handful of members from the New Black Panther Party offer a $10,000 reward for the "capture" of George Zimmerman.
Monday: Exactly one month after Martin's death, rallies across the country call for Zimmerman's arrest. In Sanford, the City Commission holds a town hall meeting on the incident and its aftermath.
Wednesday: Zimmerman's father, Robert, appears on television and says Martin threatened to kill Zimmerman and then beat him so badly, Zimmerman was forced to shoot.
Thursday: Zimmerman's brother, Robert Zimmerman Jr., appears on CNN and says medical records will prove that his brother was attacked and his nose was broken by Martin before he fatally shot the teen.
CNN's Chris Lett and Diane Laposta and the CNN Library staff contributed to this report.