What Trayvon's Family Risks in a Civil Case Against Zimmerman
I don't think they risk much at all.
This wasn't a Stand Your Ground case, so it is unlikely that Zimmerman could prevail in a SYG hearing. You can't follow someone, create a provocative situation, and then claim SYG, that's not the intent of the law.
One advantage for the Martin family in a civil case would be that Zimmerman would have to testify, he couldn't avoid it as he was able to do in the criminal trial. I don't think his credibility could hold up under cross-examination, and I think the issue of racial profiling on his part would be much clearer. I think a preponderance of the evidence would indicate he was responsible for the wrongful death of Trayvon Martin.
I think the Martin family will file a wrongful death suit against Zimmerman, both in their quest for justice, and to make sure he can't profit from Trayvon's death. But I doubt they will rush into it immediately after the ordeal of the criminal trial. They may well wait until the Justice Dept. finishes it's investigation.