Friday night, CNN's Soledad O'Brien leads a special town hall event about the killing of 17-year-old Trayvon Martin that has sparked a national dialogue on race and what it says about America. "Beyond Trayvon: Race and Justice in America." Tune in Friday night at 8 p.m. ET on CNN.
Sanford, Florida (CNN) -- Someone has stepped up, reporting to have witnessed last month's shooting of Trayvon Martin, an unarmed 17-year-old whose death has sparked nationwide controversy. The witness detailed to CNN the Florida incident from what initially sounded like an argument to its fatal conclusion.
"It would have to be starting with hearing voices, but not seeing, and then, after the voices, opening a window and then seeing -- with two men or two people on the ground, one on top of each other," the witness, who has asked not to be identified, even by gender, told CNN's Anderson Cooper about the February 26 incident in a gated community in Sanford, Florida.
The witness reported hearing through a closed window voices from an area where residents typically walk their dogs. "I thought it was rather loud, but I had just shut my window because it had just started pouring out rain," the witness said. "And then I thought, 'Oh, my gosh, who's out there walking their dog in the rain?' "
But the witness did not immediately look outside to see what the commotion was about, according to the account. "I went and did something else, and then I heard the loud voices again," said the witness, who reported opening the window. "It definitely was a very loud, predominant voice," the witness said. "I couldn't hear the words but it was like, OK, this is not a regular conversation. This is someone aggressively, you know, yelling at someone."
The witness recounted seeing two men on the grass, one on top of the other. "And at that point, not looking out the window, I heard the yell for help, one yell for help, and then I heard another ... excruciating type of yell. It didn't almost sound like 'help.' It just sounded so painful. But I wasn't watching out the window during that. And then the next time I looked out the window, there's the same thing: two men on the grass, one on top of each other. I couldn't see a lot of movement. It was very dark, but I felt like they were scuffling. And then I heard the gunshots, which, to me, were more like pops than they were like a bang."
The witness recalled hearing more than one shot. "It definitely was more than one pop noise, so I don't know if it was an echo or anything else. But it definitely made more than one pop."
The witness said the shots were audible as one man was on top of the other. But the witness recalled not having been able to see clearly which man was on top because it was dark.
Within a couple of seconds after the shots, one of the men "was walking toward where I was watching, and I could see him a little bit clearer. Could see that it was a Hispanic man. He didn't appear hurt or anything else."
But the man, who by now had left the grass and was walking on the sidewalk, did seem worried, "with his hand up to his forehead," the witness said. "Now, a couple of seconds later, in the dark, you see that person that's alive walk away; you know, obviously, OK, he must've got up and he walked away, where the other person is still laying there, face down."
The person who was walking away did not appear hurt, said the witness, who has told police of the incident. "You're thinking, wow, I'm looking at the person that just shot someone," the witness said.
George Zimmerman has told police he shot Martin in self defense.
Zimmerman's father told CNN on Thursday that Martin threatened to kill Zimmerman and then beat him so badly Zimmerman was forced to shoot.
"Trayvon Martin said something to the effect of, 'You're going to die now' or 'You're going to die tonight,' something to that effect," Robert Zimmerman told Orlando TV station WOFL. "He continued to beat George. At some point, George pulled his pistol. Did what he did."
A surveillance video from the Sanford police headquarters the night of the incident raises questions about the description of a beating.
It shows Zimmerman, his hands cuffed, exiting a patrol car and being led into the police station. First broadcast Wednesday by ABCNews.com, the video does not provide close-ups, but also does not show clear signs of injuries on Zimmerman.
Joe Oliver, a friend of Zimmerman's, said Zimmerman told him he was "cleaned up by cops at the scene" that night before being taken to the station.
Oliver also said it was discovered the next day that Zimmerman's nose was broken.
Craig Sonner, George Zimmerman's legal adviser, said Thursday the video does not support or contradict Robert Zimmerman's description. It is "very grainy," he told NBC's "Today" show. Sonner also said the injuries Zimmerman said he suffered were "later cleaned up."
A police report says Zimmerman was bleeding from the nose and the back of his head when police arrived at the scene of the killing. He was given first aid in the police car, the report says.
Sonner noted that at one point in the video, an officer appears to be looking at the back of Zimmerman's head.
Zimmerman has not been charged.
Asked whether Zimmerman is able to leave his home, given the death threats he has received, Oliver said no.
Martin's death has sparked outrage and protests across the United States, moved President Barack Obama to call it a tragedy and prompted a federal investigation.
Zimmerman's father defended the shooting in the interview with WOFL, but asked that his face be obscured because he fears for his safety.
Robert Zimmerman told the news station that Martin confronted his son first and pummeled his son.
"He was punched in the nose. His nose was broken," Robert Zimmerman said. "He was knocked to the concrete. Trayvon Martin got on top of him and just started beating him. In the face. In his nose, hitting his head on the concrete." That account appears to differ from the one provided by the witness, who said the tussle occurred on grass.
Robert Zimmerman, who was not there the night of the shooting, did not say how he knew the details of the altercation.
The elder Zimmerman's account was disputed by Martin's family attorney and several legal experts who looked at the video.
"The injuries that made it sound as though he really should have been on a stretcher are not apparent in this tape at all," said Marcia Clark, the former prosecutor in the O.J. Simpson trial. "He moves freely. He moves fluidly, not like someone who has just been through a beating in any way, shape or form, someone whose head has been pounded on the pavement as hard as described, someone whose nose was broken and bleeding. That tells you a great deal."
Sybrina Fulton, Martin's mother, said the video is among other evidence that proves her son was killed unjustly.
"I believe that this video is the icing on the cake," she said. "This is not the first part of the evidence that they have had. They have had the 911 tapes and they also have witnesses. This is in addition to what the Sanford Police Department has always had. There is no problem with this case and he needs to be arrested."
George Zimmerman, a neighborhood watch volunteer, said he shot Martin in self-defense after the teen attacked him. Martin, who was walking through the gated community back to the house of his father's fiancee, was wearing a hoodie in the rain and carrying Skittles candy and a can of iced tea he had purchased from a nearby convenience store.
Authorities have said Zimmerman has not been charged because there are no grounds to disprove his account that he acted in self-defense. Critics say Zimmerman, who is Hispanic, racially profiled Martin, who was black.
Robert Zimmerman said his son is having a hard time dealing with the criticism.
"I never foresaw so much hate coming from the president, the Congressional Black Caucus, the NAACP. Every organization imaginable is trying to get notoriety or profit from this in some way," Robert Zimmerman told WOFL. "But there's so much hate that I have never been involved in hate and George hasn't. It's really unbelievable."
Robert Zimmerman said his son is not racist and that race had nothing to do with the incident.
"He would do anything to help anybody at any time. He's colorblind when it comes to any race," Robert Zimmerman said.
Tracy Martin, Trayvon Martin's father, said Wednesday that the 911 tape shows Zimmerman was profiling his son.
In a recording of Zimmerman's call to police, some people have said they hear what sounds like a possible racial slur. CNN enhanced the sound of the 911 call, and several members of CNN's editorial staff repeatedly reviewed the tape, but could reach no consensus on whether Zimmerman used a slur.
Angela Corey, the special prosecutor assigned to investigate the case, said Tuesday that investigators would look into the allegations that Zimmerman used a racial slur.
Martin, who lived in Miami, was visiting Sanford after receiving a 10-day suspension from school, a family spokesman has said. An empty plastic bag found in his book bag had been determined to contain marijuana residue.
Benjamin Crump, Martin's parents' attorney, said information regarding the suspension is irrelevant and amounts to a smear campaign against the teen.
Florida law allows the use of deadly force anywhere a person feels a reasonable fear of death or serious injury. It has been cited in a number of justifiable homicide cases in Florida.
But as more information surfaces, the picture of what happened between Martin and Zimmerman becomes more complicated.
Despite the twists and turns, Fulton, Martin's mother, says she still has faith in authorities investigating her son's case.
"I feel confident that they're going to do a thorough investigation," Fulton said. "We're trying to be patient, even though it's been over a month. We're trying to be patient, and we're trying to press on for justice."
CNN's Umaro Djau, Deirdre Walsh, Ed Payne and Tracy Sabo contributed to this report.