Why no arrest in the Trayvon Martin shooting?

The short answer is simple:  he wasn't arrested because his self defense claim seemed plausible.

Consider the followinbg: If I were on top of a man thirteen inches shorter than me (he would be about four feet seven) and I was beating him bloody and he managed to pull a pistol from his w...aist band and shoot me. I doubt I would have been portrayed as a "victim" of murder-even if I were unarmed and toting Skittles.
(Skittles, of course, are the left’s badge of childhood and innocence)

And conversely, if I were beaten bloody by a man thirteen inches taller than I (he would be about seven foot two) I would shoot him if I had a gun.

Its common knowledge that an unarmed man can kill a much smaller person with his bare hands .
That’s why we have weight classifications in pro boxing. Men have been beaten to death by men the same weight wearing gloves. The fact martin was unarmed is not controlling in this situation.
Neither are the skittles…A big man (or "boy") can kill a smaller man without a weapon.

Six Foot three inch tall, Joran Vandersloot broke a Peruvian woman’s neck with his bare hands in his hotel room. Had the woman, who was much closer to Mr. Zimmerman’s size, had a gun, perhaps Joren Vander Sloot would have been dead, and she then would have been accused by Joran’s grieving mother of “murder”? Yep! Simple fact, she shot him, he’s dead, it’s “murder.”
That’s how the masses of sheep are assessing this situation.
It’s important to note however, the gun was not used by Zimmerman until after he was attacked by someone must larger than himself, and he fired only one shot.

If he were crazed and angry he might have emptied the gun into his "victim".

Instead he shot once and waited for the police, told them his version of what happened, they subsequently hand cuffed him, took his gun, and questioned him and eventually released him.

Possible self- defense shootings take a much longer time to investigate for obvious reasons...the police are getting a bum rap from millions people who do not know jack squat about what their findings are, or what the evidence collected at the scene reveals, or what the eye witness told the police. Remember the investigation is ongoing. It cannot be totally resolved after an hour at the scene.

Also, police are not free to blab everything they know on FB like the rest of us...who post what we "think* we know... or what Rev Sharpton tells us.

They have to be careful in making public announcements, and when they do they are usually very terse, factual, and brief-with no follow up questions are answered. That’s sop

Is Zimmerman a racsit? Read the following link:
.http://www.reuters.com/article/2012/03/25/us-usa-florida-shooting-idUSBRE82O0F820120325