I served on a Grand Jury in NJ (1 day a week for 18 weeks) - and we never had the accused or anyone from the defense in the GJ room. The only people present was the Prosecutor and the court clerk, the GJ and the person testifying. The clerk records the questions from the prosecutor and the answers from each witness. Our GJ met in a private room at the prosecutors office, not the court room, and there was no judge. We averaged about 3 to 4 cases a day - and most cases did not take very long - maybe an hour or two.
Each case started with the Prosecutor explaining the charges and the law. Then we heard testimony from people such as the victim, LE and witnesses - but never the accused.Our Grand Jury could ask the witness questions, but the prosecutor verified them prior to the witness answering. Once the witness testimony was concluded, the recorder was shut off. We could ask the prosecutor questions about the law if we had them, and we could discuss the case amongst ourselves (only inside the room), but our discussions were not recorded.
Then we voted on whether or not probable cause for LE to get involved with the accused was met, and then if it was more than likely that the accused did what they were charged with. We did not determine guilt or innocence, rather, based upon the testimony presented, was it more than likely they committed the offense, and that this case should go to trial (indict). Our GJ (about 18 people) voted; no bill= no, or true bill=yes immediately following each case, and there was a certain number of Yes, true bill votes required to move forward to trial (I forget the actual number, so I'll guess and suggest that 2/3 of the GJ must vote yes).
For those that claim a Prosecutor could get a GJ to indict a ham sandwich - I recall that our grand jury no billed many cases.