The man who shot and killed 17-year-old Trayvon Martin, setting off a nationwide outpouring of anger, told police that Martin knocked him down with a single punch and slammed his head into the sidewalk several times - an account that police said witnesses have corroborated, according to The Orlando Sentinel.

George Zimmerman, 28, has gone into hiding, and his account of what happened one month ago hadn't previously emerged as demands for his arrest grew louder.

The Orlando Sentinel reported Monday that police said Zimmerman has described and re-enacted the events this way:

Zimmerman, a neighborhood watch captain, was walking back to his SUV when Martin approached him from behind. The two exchanged words, and Martin decked him with a punch to the nose and began beating him. He told police he shot Martin in self-defense.

Witnesses said they heard someone cry out in distress, some of them telling NBC News and other news organizations that it was Martin. But police told the Sentinel their evidence indicated it was Zimmerman.

Zimmerman's attorney, Craig Sonner, has suggested that he will invoke Florida's "stand-your-ground" law, which provides significant leeway for people to use deadly force if they feel their lives are in danger. Angela Corey, the special prosecutor reviewing the case, said that would make getting a conviction "more difficult than a normal criminal case."

"The stand-your-ground law is one portion of justifiable use of deadly force," prosecutor Angela 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."

Corey added that it's also not clear whether prosecuting the death as a hate crime would lead to a conviction. Martin was black; Zimmerman's father is white and his mother is Hispanic.

"It would depend on which charge, if any, we're able to file," said Corey, whom Gov. Rick Scott appointed to review the case. "Before we would be able to determine, one, if this is a hate crime, and two, whether or not that would enhance the crime."

Sonner, Zimmerman's attorney, said Monday on NBC's TODAY show that "George Zimmerman is absolutely not a racist." Joe Oliver, a friend of Zimmerman's, described him on the show as being "dedicated," not obsessed, with his duties as neighborhood watch captain.

"I'm a black male, and all that I know is that George has never given me any reason whatsoever to believe he has anything against people of color," Oliver said Sunday.

Sonner and Oliver said they had decided to talk to the news media because of what they believe is a one-sided portrayal of what happened.

Also Sunday, "Dateline NBC" aired an interview with a woman who said she and her roommate heard and saw the last moments of Martin's life.

Dateline NBC interviews woman who saw aftermath

Mary Cutcher said they heard the voice of what sounded like a young person in distress just before hearing a gunshot.
"It sounded young," she said. "It didn't sound like a grown man is my point."

She added that as they looked out from their apartment they saw Zimmerman "straddling the body, basically, a foot on both sides of Trayvon's body and his hands pressed on his back."
Zimmerman then told them to call the police, Cutcher said. "Zimmerman never turned him over or tried to help him or CPR or anything."