Sunday evening, Feb. 26: It was raining in Central Florida while the NBA All-Stars game and the Oscars were about to begin on TV. A 17-year-old high school junior from Miami Gardens serving a 10-day suspension went to 7-Eleven to get candy. It was the third time Trayvon Martin was disciplined at school, so this time his parents sent him up to a quiet, racially mixed, gated community in Sanford with his dad to get his priorities straight. He was black and wore a hoodie. George Zimmerman, a 28-year-old neighborhood watch volunteer who routinely called police to report anything awry, had just made dinner and told his family he was headed to Target. He was Hispanic and wore a holstered Kel Tek 9mm semiautomatic handgun. The brief encounter between the two at the Retreat at Twin Lakes community would leave one dead and the other in hiding, give rise to a social movement and, at least temporarily, cost the local police chief his job. In the next 30 days, the name "Trayvon" would be tweeted more than 2 million times. In a fast-paced world of 24-hour cable news and nonstop social media, what happened that night has become both common knowledge and a blur of unattributed rumor accepted as fact. A controversial police report incited conspiracy theories and failed to definitively resolve what everyone wants to know: Who picked the fight? Armchair crime scene investigators around the nation insist on access to the evidence, and millions more demand an arrest in a case now being looked at by at least three agencies, including the FBI. The protagonists in the saga gripping the nation are Zimmerman, a man with a history of going after suspects in hot pursuit, and Trayvon, a chronically tardy teenager who liked aviation, was making plans for college and got suspended for having a small empty plastic bag containing marijuana residue. Their story begins when Zimmerman got out of his vehicle and pursued Trayvon on foot. But in the tale pieced together from 911 calls, witnesses, police, Zimmerman's family and the girl who was on the phone with Trayvon in the last minutes of his life, a key one-minute gap remains a mystery that may never be solved: Who approached whom? Who threw the first blow? And the key question a special prosecutor in Jacksonville is now tasked to investigate: Did Zimmerman justifiably take Trayvon's life to save his own? The encounter Trayvon, a junior at Dr. Michael M. Krop High, was a lot like most teenagers: He spent an inordinate amount of time on the phone. On that Sunday, he talked for nearly five hours. Earphones in his ears, Arizona iced tea in hand and a cellphone, Skittles and $22 in his pockets, he chatted the whole way back from the store. It started raining harder as he walked, so he pulled up his hood and sought shelter at one of the buildings in the townhouse complex, the girlfriend he was chatting with on the phone told attorneys. At 7:11 p.m., Zimmerman, who was in his truck, spotted Trayvon. There had been a rash of burglaries in the neighborhood attributed to young black men, and Zimmerman was wary of someone he did not recognize walking along the path that goes through the back of the townhouses, his father later told a local TV station. Zimmerman called police. Records show it was the fifth time in a year that he had alerted authorities to the presence of a black male he found suspicious. This one, he said, looked high and had something in one hand while he kept the other in his waist as he peered at houses. "Hey, we've had some break-ins in my neighborhood, and there's a real suspicious guy," he told the police operator. "This guy looks like he's up to no good, or he's on drugs or something. It's raining, and he's just walking around looking about." Trayvon spotted something suspicious, too: He was being followed. A T-Mobile phone log provided by the family's attorney shows Trayvon's girlfriend called him again at 7:12 p.m., just moments after having hung up with him. "I think this dude is following me," Trayvon told her, according to her account to family attorney Benjamin Crump. The girl says she offered Trayvon advice: "Run!" "When he said this man was behind him again, he come and say, this looks like he's about to do something to him," the girl told ABC News. "And then Trayvon come and said the man was still behind him, and then I come and say, 'Run!' " Trayvon did just that. At 7:13, two minutes into Zimmerman's call, he tells the police operator: "S---, he's running." A beeping sound is heard, indicating that he has opened his car door. Zimmerman went after Trayvon and, out of breath, muttered profanities. He lost sight of him. "Are you following him?" the operator asked. "Yeah." "Okay, we don't need you to do that." Zimmerman spent almost two more minutes offering directions to the operator. He said he'd meet police by the mailboxes and then, just before hanging up, apparently thought the better of it. "Actually, could you have him call me, and I'll tell him where I'm at?" he said three minutes and 50 seconds into the call. At 7:15, he hung up . Lawyers for Trayvon's family say Zimmerman's decision not to wait for police by the mailboxes and instead be reached by phone proves he planned to keep looking for the teen instead of simply waiting for a patrol car. The two met up along a dark paved path that runs between the back of two rows of townhouses. The girl on the phone told Crump that she heard the two exchange questions, like "Why are you following me?" and "What are you doing here?" Zimmerman's father told an Orlando TV station that it went more like, "Do you have a f----ing problem?" to which George Zimmerman replied "no" and reached for his phone to call police a second time. Zimmerman, a married insurance underwriter who studied criminal justice at Seminole State College, told police that Trayvon approached him from behind as he was returning to his car. He told police, his family and his attorney that Trayvon decked him in the nose hard, causing him to hit the ground. Then, he says, Trayvon started punching him and slamming his head on the concrete. "It's my understanding Trayvon Martin got on top of him and just started beating him in the face, in his nose, hitting his head on the concrete," Zimmerman's father, Robert, told Orlando's Fox35. The girl who said she was talking to Trayvon told the attorney that she heard a scuffle until the line went dead. Her four-minute call ended at 7:16. Shooting, witnesses Although the Sanford police would not reveal the times, from 911 tapes it is known that the first of the calls from residents came while Zimmerman and Trayvon were still fighting. Desperate wails are heard in the background of at least one 911 call. Two witnesses have said they saw the encounter, but their stories contradict each other. One man interviewed by a local Fox news station, who asked to be identified only as John, said he saw the man wearing a red jacket — Zimmerman — on the ground, being beaten by someone on top of him — Trayvon. "The guy on the bottom, who I believe had a red sweater on, was yelling to me 'Help, help,' and I told him to stop and I was calling 911. I got upstairs and looked down. The person that was on top beating up the other guy was the one laying in the grass, and I believe he was dead at that point," he said. But last week another unidentified man told CNN that he saw a larger man on top and a boy underneath. There wasn't much movement, he said. Zimmerman's father told the Orlando TV station that as his son was being beaten he tried to move from the concrete onto the grass. In doing so, he said, the gun his son kept in a holster on his waist was exposed. "Trayvon Martin said something to the effect of 'You're going to die now' or 'You're gonna die tonight' — something to that effect," Robert Zimmerman said. "He continued to beat George. At some point, George pulled his pistol and did what he did." Seven calls came in to 911. "They're wrestling right in the back of my porch," one caller said. "A guy is yelling, 'Help.' … I'm pretty sure the guy is dead." "I saw a man lying on the ground and he needed help, screaming," one 13-year-old boy told 911. "I heard a loud sound, and the screaming stopped." Selma Mora Lamilla heard no fighting, only what she says was the wail of a child and the distinct crack of gunfire that silenced it. She ran outside her back porch, where she said she saw Zimmerman standing above Trayvon, apparently holding him down. "I asked him, 'What's happening here? What's going on?' " Mora said. "The third time, I was indignant, and he said, 'Just call the police.' Then I saw him with his hands over his head in the universal sign of: 'Oh, man, I messed up.' " Police arrive The police arrived at 7:17. Trayvon was dead. The first officer to arrive was Timothy Smith, who found a white man in a red jacket and jeans standing and a black male in a gray hoodie facedown in the grass. Smith later wrote: "Zimmerman stated that he had shot the subject, and he was still armed. … Located on the inside of Zimmerman's waistband, I removed a black Kel Tek 9mm PF9 semiauto handgun and holster. While I was in such close contact with Zimmerman, I could observe that his back appeared to be wet and was covered in grass, as if he had been laying on his back on the ground. "Zimmerman was also bleeding from the nose and back of his head." Officer Ricardo Ayala and Sgt. Anthony Raimondo attempted CPR on Trayvon until Sanford Fire Rescue arrived. A paramedic pronounced Trayvon dead at 7:30. Zimmerman was handcuffed and placed in the back of Smith's patrol car. Sanford Fire Rescue administered first aid. "While SFD was attending to Zimmerman, I overheard him state, 'I was yelling for someone to help me, but no one would help me,' " Smith wrote. That someone shouted is corroborated by 911 callers, who reported hearing screams for help just before they heard gunfire. One woman sobbed for 14 minutes, because she felt guilty for not having given aid. It remains unclear which of the two cried out for help. All the callers now believe the person who cried for help is the one who ended up dead; the parents of Zimmerman and Trayvon are each convinced that it was their son screaming for help. The detention Zimmerman was taken to the Sanford Police Department in handcuffs. A time stamp on the precinct security camera video shows Zimmerman got to the police station at 7:52 p.m. An officer patted him down at that time. The video shows no obvious sign of injury or bloodstains on his clothes, although one shot shows an officer examining the back of Zimmerman's head, then wiping his hands on his uniform pants. Meanwhile, police fingerprinted the dead teen, who carried no ID. He had never been arrested, so 12 hours passed before anyone knew his name. "I have never seen a crime scene cleaned up so fast," Trayvon's father, Tracy Martin, told the Miami Herald. He came home that night just before 11 p.m. and saw no trace of a crime. It was not until he called police the next morning that a major-crimes detective went to the townhouse where his girlfriend lives to break the news. Zimmerman, in the meantime, had been questioned by police and released without charges. Police stressed that Zimmerman was interviewed at least three times and gave a videotaped statement and a walk-through of what happened. Zimmerman, whose father is a retired Virginia magistrate, never asked for an attorney or changed his story, former Sanford police Chief Bill Lee said. The investigation The investigation began with detectives interrogating Zimmerman and patrol officers canvassing the 911 callers. One caller said he had seen a man with a white T-shirt on top of the other. Neither Zimmerman nor Trayvon wore white T-shirts. Another caller, Mora's roommate, Mary Cutcher, phoned police after the gunshot and said the black man was standing over another man, which would have been impossible, because Trayvon was already dead. Cutcher later blasted the Sanford police, saying detectives did not return her phone calls because she clearly believed that the person crying was the boy, and that was not the story investigators were looking for. Police issued a news release saying she had given an "inconsistent statement." ABC News later reported that a boy who witnessed part of the incident said he saw someone matching Zimmerman's red-jacket description lying on the grass, suggesting the shooter had told the truth when he said Trayvon had knocked him down. But the boy, 13-year-old Austin McLendon, gave 911 and the Miami Herald a different account. "He never said he saw someone in a red shirt or someone on top of another person — someone is switching his story," said Austin's mother, Cheryl Brown. "The police came here and asked him leading questions like, 'The first person had a red shirt?' because they wanted him to say, 'Yes, the person had a red shirt.' " Brown said she will hire an attorney to demand a copy of the audio statement her son gave to prove he has never wavered, and never claimed to see Zimmerman on the ground. Florida Department of Law Enforcement investigators were at the gated community last week, reinterviewing witnesses. The probe is also expected to lean heavily on audio experts to try to determine whether it was Trayvon or Zimmerman crying in the first 911 call. Several days passed before police released a report with an account that said Zimmerman had blood on his nose and the back of his head, fueling suspicion that the department was attempting to bolster Zimmerman's story and defend the lack of an arrest. The report listed the height and weight of every person, including the 911 callers. The only person whose size is not noted is Zimmerman. At 5 feet 9, Zimmerman was much shorter but heavier than Trayvon. The report listed Trayvon at 6 feet and 160 pounds, though his family said he was actually 6-foot-3 and weighed at most 150 pounds. Although some people thought they heard two shots, a review of the confiscated weapon showed that only one shot was fired, a police spokesman told the Miami Herald. Much has been made by people critical of the investigation of the fact that Zimmerman was not tested for drugs or alcohol, although Miami police experts say homicide suspects are rarely tested unless it's a DUI case. The Seminole County State Attorney's Office was called the night of the shooting, as is routine with all killings, but no one from the office went to the scene. It is unclear who gave the order to let Zimmerman go. Although police publicly said there was no probable cause to arrest Zimmerman, it was later revealed that early on investigators did request an arrest warrant from the state attorney's office, which held off for further review. The case has since been reassigned to a special prosecutor in Jacksonville. The Sanford police and the Seminole state attorney have referred questions to special prosecutor Angela Corey. Her office said it will not answer any inquiries about the case. Much of the evidence, such as the autopsy report, which would show results of Trayvon's toxicology test, are not yet public record. Police have declined to release Zimmerman's statements or that of the witnesses. The Fort Lauderdale funeral director who handled the arrangements for Trayvon's family has told reporters that he saw no bruises or blood on the teen's knuckles. Police said Zimmerman provided medical records to support evidence of his injuries. In an interview two weeks after the incident, Lee said witness statements and physical evidence backed up Zimmerman's version of events. He suggested that based on the timing of the call, he believed that Trayvon went out of his way to approach the person tailing him and mouth off. "If Trayvon has made it that far, and Zimmerman is getting out of his truck, why doesn't Trayvon keep walking?" Lee said. "He's 70 yards from his house. I think based on the timing of the call and Zimmerman losing sight of him that he had made it to that 'T' (at the end of the path) and was starting to walk toward his house. "My wish is that he would have kept walking." In the midst of public fury over his handling of the incident, Lee stepped down from his post. Reached by the Herald on Friday, he declined to discuss the case. "We can't discount (Zimmerman's) story, based on — not evidence we put anywhere, not testimony we put in anybody's mouth — but testimony of witnesses who were there, that called, and the physical evidence that's there. You can't refute it," Lee said in the early interview. "The conclusions that are drawn from the basic information is that George Zimmerman shoots a 17-year-old kid with a bag of Skittles and an Arizona iced tea can. And you know, those are facts: George Zimmerman did shoot Trayvon Martin, and Trayvon Martin did have a bag of Skittles and an Arizona iced tea. "The fact that he had a bag of Skittles and an Arizona iced tea does not have anything to do with the facts of why George Zimmerman thought he needed to use deadly force."