Family is family. If he did what he is accused of, then he should be prosecuted. However don't start asking me to turn family and friends into the national government. But I don't think you're going to be able to understand the mindset of folks like this. They did it to protect him.
Unless he is direct family, I can't be at all sympathetic to them. Even if he is, I have a hard time with it.
I consider the Unibomber's brother to be a bit of a hero. It took great courage for him to turn in his brother. It also was the right thing for him to do.
What if one of them was involved in bringing down the Twin Towers?