Stand Your Ground and Trayvon Martin

More reporting on the killing of Trayvon Martin:

The teenager went out to get some Skittles and a can of ice tea. On his way back into the gated suburban Orlando community, Martin, wearing a hood, was spotted by Zimmerman, 26. According to law enforcement sources who heard Zimmerman's call to a non-emergency police number, he told a dispatcher "these a..holes always get away."

Zimmerman described Martin as suspicious because he was wearing a hooded sweatshirt and walking slowly in the rain, police later told residents at a town hall. A dispatcher told him to wait for a police cruiser, and not leave his vehicle. 

But about a minute later, Zimmerman left his car wearing a red sweatshirt and pursued Martin on foot between two rows of townhouses, about 70 yards from where the teen was going. Lee said Zimmerman's pursuit of Martin did not of itself constitute a crime.

Witnesses told ABC News a fist fight broke out and at one point Zimmerman, who outweighed Martin by more than 100 pounds, was on the ground and that Martin was on top. Austin Brown, 13, was walking his dog during the time of the altercation and saw both men on the ground but separated. 

Brown along with several other residents heard someone cry for help, just before hearing a gunshot. Police arrived 60 seconds later and the teen was quickly pronounced dead. According to the police report, Zimmerman, who was armed with a handgun, was found bleeding from the nose and the back of the head, standing over Martin, who was unresponsive after being shot. 

An officer at the scene overheard Zimmerman saying, "I was yelling for someone to help me but no one would help me," the report said. Witnesses told ABC News they heard Zimmerman pronounce aloud to the breathless residents watching the violence unfold "it was self-defense," and place the gun on the ground.

I don't know how reliable this account is. The sourcing isn't really stated with clarity.

There's some talk in comments that Zimmerman still has to prove -- by some objective standard -- that he believed his life was endangered, or that he was going to suffer serious injury. CNN's legal expert says differently, asserting that in a case without witnesses (to the shooting) Zimmerman's word is all they have.

This is not my area of expertise, and I am open to being wrong, but it really seems like the cops and maybe the state's attorney don't think they have much of a shot at disproving Zimmerman's claim of self-defense. Based on the murky facts presented, and without assuming motives, that's the only way I can understand claims like this one from the police --"Until we can establish probable cause to dispute [self-defense], we don't have the grounds to arrest him."

I think what's most frustrating about this sort of case, is you can have someone hovering at the edge of the law, escalating a situation, and then retreating behind the law's full weight when the awful consequences are made evident. You don't want to hear me say this again, but all I can think about is my old friend, Prince Jones. In both cases, I could easily see myself having the same reaction, and ending up the same way.