The Orlando Sentinel reported Monday authorities said on the night of the Feb. 26 incident and in subsequent meetings George Zimmerman described and re-enacted what he said happened. He told police he had followed the youth because he was behaving suspiciously but turned around after losing sight of him.
Also Monday, hundreds gathered in Sanford, Fla., for a rally in support of Martin and The Miami Herald reported school police had found women's jewelry and what they described as a "burglary tool" in Martin's backpack in October, leading to suspension from school but no arrest.
Zimmerman told authorities he was walking back to his sport utility vehicle when the 17-year-old approached him from behind. The two exchanged words, with the teen asking the Zimmerman volunteer if he had a problem and when the man replied no, allegedly said something to the effect "Well, you do now," the Sentinel said.
Zimmerman said Martin knocked him to the ground with one punch, then jumped on him and slammed his head into the sidewalk several times so hard he was bloodied and battered, the Sentinel said. He said he then shot Martin, who was unarmed, once in the chest from close range in self-defense.
ABC News reported a police source quoted Zimmerman as saying the youth had tried to get his gun.
Zimmerman received medical attention at the scene and then was taken in a police cruiser to a police station for questioning.
Authorities told the newspaper much of Zimmerman's account has been corroborated by witnesses.
Zimmerman, who is white, had told a 911 dispatcher he was following the black teen because he looked suspicious. "We don't need you to do that," the dispatcher said.
ABC News said Martin's girlfriend said in a recording it obtained that she heard him ask Zimmerman, "'Why are your following me,' and then the man asked, 'What are you doing around here?'" She said she heard the two scuffle before the line went dead.
The network said Austin Brown, 13, told investigators he saw a man matching Zimmerman's description lying on the grass moaning and crying for help just moments before he heard the fatal gunshot.
Citing a Miami-Dade Schools Police report, the Herald reported Martin was suspended from school in October after a school security employee reported finding women's jewelry and a screwdriver that the school employee characterized as a "burglary tool" in Martin's backpack. Martin claimed a friend gave him the jewelry, which turned up during a search of his backpack for a graffiti marker.
Martin was suspended for graffiti, four months before he was suspended again -- this time for possession of an empty plastic bag that contained marijuana residue. The Herald reported Monday the suspension was also for possession of a "marijuana pipe."
"It's irrelevant to what happened on Feb. 26, does not change material facts of the situation, specifically that had George Zimmerman not left his vehicle and heeded the police dispatcher's guidance, we wouldn't be here today," family spokesman Ryan Julison said regarding the latest suspension.
Martin's family has acknowledged he had been suspended for tardiness and truancy.
Ben Crump, an attorney for Martin's parents, told the Herald they had not known about the jewelry, which he said was "completely irrelevant to what happened Feb. 26."
"They never heard this, and don't believe it's true," Crump said. "If it were true, why wouldn't they call the parents? Why wasn't he arrested?
"We think everybody is trying to demonize him."
Martin's mother, Sybrina Fulton, said, "They killed my son and now they are trying to kill his reputation," the newspaper reported.
State Attorney Angela Corey, the lead prosecutor in the case, said it may be tough to get a conviction, noting Florida's "stand-your-ground law," which allows a person to use deadly force if attacked.
"The stand-your-ground law is one portion of justifiable use of deadly force," Corey told ABC News. "And what that means is that the state must go forward and be able to prove its case beyond a reasonable doubt. ... So it makes the case in general more difficult than a normal criminal case."
The shooting and the fact Zimmerman has not been arrested or charged have sparked widespread protest and outrage by many who perceive the case as a matter of racial profiling.
Craig Sonner, a lawyer representing Zimmerman, has told ABC News he would likely invoke the stand-your-ground law.
When Zimmerman shot Martin, he thought "one of them was going to die that night," Sonner said.
The U.S. Justice Department and the FBI are investigating the case as a possible hate crime.
ABC News said there's enormous pressure from local and state authorities for Zimmerman's arrest.
Corey said if Zimmerman is charged, it might not happen for weeks.
Hundreds of students at Dr. Michael M. Krop Senior High, the school Martin attended, dressed in black Monday to protest, the Herald reported.
Students protested last week at more than 30 Miami-Dade schools and staged walkouts at about 10 schools in Broward County.
The Rev. Jesse Jackson, Baltimore Ravens linebacker Ray Lewis, civil rights activist and MSNBC personality the Rev. Al Sharpton and comedian Sinbad attended a special meeting of the city commission meeting, where several speakers urged officials to -- in the words of National Urban League President Marc Morial -- "go on the record in support of the arrest of George Zimmerman."
Sharpton said the city's reputation is at risk, the Orlando Sentinel reported.
"You are risking going down as the Birmingham and Selma of the 21st century," Sharpton said.
"If a black vigilante shot a white child, he would be in jail right now," the Rev. Jesse Jackson said. "And maybe he should be."
Joe Oliver, a former CNN anchor and a friend of Zimmerman's, appeared on television Sunday to support Zimmerman's version of events.
"That sounded like someone in dire need of help," Oliver said. "That sounded like George."
Martin's mother, Sybrina Fulton, said Sunday she hoped the case leads to changes in the stand-your-ground law.
"I think people are really sick and tired of the same situation," she said. "I also think they can relate to our situation because they have young men in their households and it breaks their heart just like it breaks our heart.
"It's just good to know that we have that type of support, and that we have a community, we have a movement of people that want to see justice for Trayvon Martin."
She is expected to testify Tuesday before Congress, the Herald said.