Why can't they convene a 2nd grand jury ?

[ctaylors6]

22. I have question about the prosecutor(s)

I started to post this somewhere else but decided this thread may be better place. I've started reading the transcripts, and McCulloch isn't the one questioning the witnesses; two other people are - Ms. Whirley and Ms. Aliadeh.

After some googling, I found and read this article:
http://www.washingtonpost.com/politics/in-atypical-approach-grand-jury-in-ferguson-shooting-receives-full-measure-of-case/2014/09/07/1dec6ffe-339b-11e4-8f02-03c644b2d7d0_story.html

It says: "McCulloch declined to step aside, but he is not presenting evidence to the grand jury, which usually means he won’t try the case himself, Magee said. But he is supervising the two attorneys in his office — Sheila Whirley and Kathi Alizadeh — who are presenting to the grand jury."

The article is dated 9/7. Does anyone know if Whirley and Alizadeh presented all the evidence or if McCulloch stepped in at some point? I'm not saying it made difference to outcome, but it just surprised me that I hadn't heard about this before today.

Thanks!