No doubt Zimmerman's conduct lead to Martin's death. But the question is exactly what Zimmerman is guilty of. Without actual film footage, we don't know that Martin didn't turn on Zimmerman, & pursue him, perhaps because he believed Zimmerman was also a threat. This could explain Martin's attacking Zimmerman just before he was shot. Unfortunately (or fortunately), in our legal system, we cannot convict based upon the rough likelihood of what happened. If we could, the jury I served on would've convicted the accused even though there was scant evidence. But the women on the jury found him scary enuf that they wanted to put him away because he might've done it. I badgered them into following the instructions we were given, ie, do not convict if there's reasonable doubt. The system is lousy, but it's better than we as a people are.