SANFORD, Florida (CNN) -- George Zimmerman's brother said medical records will prove that his brother was attacked and his nose was broken by Trayvon Martin before he fatally shot the teen.
Robert Zimmerman Jr. spoke to CNN's Piers Morgan Thursday night saying he wanted to correct some of the "mythology" and untruths that have been spread about the controversial shooting.
The shooting of Martin, an unarmed 17-year old, has sparked an intense national debate about race, birthed protests and was addressed by President Barack Obama who called the incident a "tragedy."
Robert Zimmerman Jr. also called the shooting a tragedy but warned that the some of the responses have not been healthy.
"This is a tragedy. Her son was lost," he said trying to send a message to Martin's mother. "I feel very badly about that and I want, in the end, not for her son's memory to be seen as how we degraded our system and turned it into mob rule and went into a hate speech. Ultimately, we all wish that this was a different situation."
George Zimmerman has told police he shot Martin in self defense, in the incident that occurred on February 26 incident in a gated community in Sanford, Florida.
Zimmerman's father said on Wednesday that Martin threatened to kill Zimmerman, broke his nose and beat him so badly that Zimmerman was forced to shoot the teen. Robert Zimmerman Jr., on Thursday, told the same story.
"You return force with force when somebody assaults you. George was out of breath, he was barely conscious," the brother said. "There would have been George dead if he had not acted decisively and instantaneously in that moment when he was being disarmed."
Martin's family and legal experts have questioned the Zimmerman's family version after the recent release of surveillance videos from the Sanford police headquarters the night of the incident.
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.
"We now have pictures of Mr. Zimmerman walking into the police station, and you see no injuries that would have come from abrasions on a sidewalk," said Lou Palumbo, a retired police officer who owns a private security firm.
"Anyone who's seen a broken nose is aware of the fact that the blood spurts. That leads to a lot of bleeding. You would have expected to see blood on the front of George Zimmerman's shirt collar. Blood -- you know, in many more places," said Marcia Clark, the former prosecutor in the O.J. Simpson trial.
Robert Zimmerman Jr. said his brother was treated at the scene before he was taken to police headquarters and it appears to him that the surveillance tape shows that his brother had injuries.
"We're confident the medical records are going to explain all of George's medical history," Zimmerman Jr. said. "His nose looks swollen in that video. I'm his brother."
Sybrina Fulton, Martin's mother, has 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 last month. 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.
A witness of the incident also spoke to CNN Thursday.
"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 incident.
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.