If that happened, a few things probably would have happened. The prosecution would have dropped the murder charge for sure, which was stupid to bring to begin with and Zimmerman would have used a Stand Your Ground defense actively and on the law probably would have at least come out with another mistrial.
... and if this case was not so much in the news, there probably would not be a second trial
You're probably right, and there wouldn't have been ONE trial if it wasn't for public outcry. But it's still a problem endemic in the justice system.