The only witness of the case says that Zimmerman was being beaten by Trayvon.
There is no evidence of wrong-doing. All signs point to rational self-defense. Zimmerman should not be arrested. The prosecutor has no case.
Although, Zimmerman and his lawyer prefers the custody of jail at this time.
The 911 call with someone screaming for mercy and help is still there. Shooting someone who is begging to be spared is not self-defence. So if it was the child screaming, the prosecutor has a very strong case.
It is indeed self-defense if Trayvon was a threat beforehand. Assault and attempting to cease a weapon warrants a gun shot. The threat had to be eliminated.
Also, Trayvon was no child at the time of the shooting. He was a built, mature young man.