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.

"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."

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.

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 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."

immerman's lawyer, when shown part of the interview being aired Sunday night on Dateline, emphasized that his client would be claiming self-defense.

"I think there were efforts made to render aid to Trayvon," Craig Sonner told NBC's TODAY show.

Mary Cutcher told Dateline that she and her roommate both saw Zimmerman "straddling the body, basically a foot on both sides of Trayvon's body, and his hands pressed on his back."

Cutcher added that Zimmerman told her and her roommate to call the police.

"Zimmerman never turned him over or tried to help him or CPR or anything," Cutcher said.

Sonner also reiterated what he had said in recent days, that Zimmerman suffered a broken nose and a gash to the back of his head.

In the final moments of his life, Trayvon Martin was being hounded by a strange man on a cellphone who ran after him, cornered him and confronted him, according to the teenage girl whose call logs show she was on the phone with the 17-year-old boy in the moments before neighborhood watch volunteer George Zimmerman shot him dead.

Martin's death Feb. 26 has stirred national outrage and protests, partly prompting the U.S. Justice Department's Civil Rights Division and the FBI to open an investigation into the case.

ABC News was there exclusively as the 16-year-old girl told Martin family attorney Benjamin Crump about the last moments of the teenager's life.

"He said this man was watching him, so he put his hoodie on. He said he lost the man," Martin's friend said. "I asked Trayvon to run, and he said he was going to walk fast. I told him to run but he said he was not going to run."

Eventually he would run, said the girl, thinking that he'd managed to escape. But suddenly the strange man was back, cornering Martin.

"Trayvon said, 'What, are you following me for,' and the man said, 'What are you doing here.' Next thing I hear is somebody pushing, and somebody pushed Trayvon because the head set just fell. I called him again and he didn't answer the phone."

The line went dead. Besides screams heard on 911 calls that night as Martin and Zimmerman scuffled, those were the last words he said.

Trayvon's phone logs, also obtained exclusively by ABC News, show the conversation occurred five minutes before police first arrived on scene. The young woman's parents asked that her name not be used, and that only an attorney could ask her questions.

Martin's father, Tracey Martin, and mother, Sybrina Fulton, listened to the call along with ABC News, ashen-faced.