If I remember correctly, this grand jury began their task the week after or two weeks after Stacy disappeared. I agree that it would be difficult to bring in new jurors at this juncture as there's been so many witnesses that have already testified. It would be difficult to bring new grand jurors up to speed.
I wonder if the grand jury includes alternates, who have been there and listened to all the witness testimony, and who could be seated as a grand juror if someone on the grand jury can't continue for another four months. In the time since this grand jury began meeting, it's very possible for a juror to become ill or for some reason is unable to attend a session or two of the proceedings, so there must be something in place to cover this possibility.
