(CBS News) SANFORD, Fla. - Newly-released video of the man who shot and killed Trayvon Martin shows George Zimmerman with no apparent injuries, right after he claims Martin attacked him.
That is raising new questions about Zimmerman's claim of self-defense.
But Zimmerman's father insists the unarmed teenager was the aggressor and Zimmerman had no choice but to do what he did.
The police video, obtained by ABC News, shows Zimmerman, in handcuffs, being led into Sanford police headquarters the night he killed Martin.
Zimmerman shows no obvious head injuries, but at one point, an officer inspects the back of his head. Zimmerman spent five hours telling police he shot Martin in self-defense.
And in an interview with WOFL-TV in Orlando, Robert Zimmerman, the gunman's father, said his son told him he spotted Martin and called police to report a suspicious person, then followed him. He turned around, says Robert Zimmerman, and there was Martin.
He claims Martin then approached his son, cursing at him. As the younger Zimmerman reached for his cell phone, Martin punched him, breaking his nose and knocking him to the ground, Robert Zimmerman contends."Trayvon Martin got on top of him and just started beating him," claims the father.
That, says Robert Zimmerman, is when Martin threatened to kill his son. George Zimmerman pulled out his firearm and shot Martin.
No witness saw how the fight started.
On a 911 tape, someone was yelling for help before the sound of a gunshot - but it is unclear who.
"You think he's yelling help?" the police dispatcher asked.
"Yes," said the caller.
Then the gunshot is heard.
"There's gunshots!" the woman on the phone said.
"Everyone that knows George," asserts Robert Zimmerman, "knows absolutely that that is George screaming. There's no doubt in anyone's mind.
But Sybrina Fulton, Trayvon's mother, heard it differently.
Asked earlier this month if she recognized the voice on the tape, she replied, "That's my baby. That's my son that was yelling."
Two parents. Two sons. Two different takes on the voice on that tape.
The special prosecutor has told us she'll hire a voice recognition expert, hoping to find the truth.
To see Mark Strassmann's report, which includes the police video, click on the video in the player above.