Grand juries don't usually operate that way. There had to be consensus among at least nine of 12. They could have simply not indicted anyone if there was no clear indication who killed her. Instead, there are some very specific counts indicting John and Patsy
that do not include first degree murder.
And keep in mind there were other counts that were not released. What are those about? If they involved John and Patsy they should have been included. However, as I cited above, they could have been withheld from the open records law if there was discussion of a living minor contained within them.
Here's an old think with some info about how grand juries work, and specifically with regard to the JBR GJ.
http://extras.denverpost.com/news/jon185.htm
This is an interesting quote, particularly as it was made before Alex Hunter had to deal with his grand jury's indictments:
But a prosecutor is playing "a wild card'' when he sends a case to a grand jury, said Mueller, the CU law professor.
[FONT=arial, verdana, sans-serif]Conferring immunity on the wrong witness can doom a case. And in rare instances, the grand jurors and the prosecutor may disagree about how to proceed, leading to a "runaway'' grand jury.
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After reviewing everything known to date, my best guess is that after the GJ returned the true bills, Hunter was faced just such a "runaway grand jury". He had a murderer he could not prosecute with accomplices he chose not to prosecute given the challenges of proving a case with such a botched initial investigation and knowing the Ramseys would have the best attorneys money could buy. And even if he felt he could prove it, he still doesn't end up with a convicted murderer no matter what. [/FONT]