Eyewitnesses say that they saw Martin attacking Zimmerman. Their stories matched Zimmerman’s story. Martin was also not an angel like his family is portraying him. He was suspended from school for marijuana possession. A deleted Twitter account was found through web archives which had pictures of him dressed as a gang member, making gang signs, and writing very violent messages.
Not all liberals are supporting Martin. They are against the law in Florida. I don’t know enough about it, so I can’t speak for it, but it appears that Zimmerman did follow the law. If you don’t like the law, fine, try and change it. But don’t fault someone for following the law as it exists.