For my story, I want a character who is a cop (probably doesn't make a difference in this case) to see a witness testimony in a grand jury hearing. But from what I can tell, grand jury hearings are not open to the public, so does that pretty much mean there is way to get in and see what a witness is going to say?

Or I could set it in a state that has preliminary hearings instead of that is better since they seem to be more open to the public in my research. Unless there is a way a person can hear what a witness testimony will be somehow?