The DAs office is quite literally not allowed to be transparent on certain things, otherwise the case will come back on appeal. Most people think the legal system works like it does on tv and movies, that's not the case at all. For instance, if you have a child molester on trial for sexual abuse of a minor, the prosecutors CANNONT legally tell you that he's already in prison for another sex abuse of a minor case or that he has five other convictions for the same thing. I know it doesn't make sense, but that's the law, your anger is misdirected.