The prosecutor decided that Wilson would not be charged;
Clearly the prosecutor did not believe the evidence justified an indictment. He didn't really do anything to conceal that; he publicly acknowledged that in presenting the evidence to the Grand Jury that he wasn't making any recommendation to them on whether or not to indict.
Normally when a prosecutor doesn't believe the evidence merits an indictment, he doesn't take the case to a Grand Jury; he simply uses his prosecutorial discretion not to file charges.
However this was anything but a normal case. Because of the enormous political dimensions, the ongoing community unrest, and the 24/7 media circus, Mr. McCulloch (who is after all an elected official, and thus a politician) decided he wasn't going to make himself the last word in the matter so he made the decision to present all of the evidence, (not just evidence that might support an indictment) to the Grand Jury for a decision.
(BTW, for anyone who thinks for whatever reason that McCulloch shouldn't have been the DA in this case, I would point out that very early on, he publicly asked that if Gov. Nixon wanted to take the case away from him and appoint a special prosecutor, he should do it. Nixon chose not to do so.)
Using the Grand Jury process in this way is unusual, (again, this is an unusual case) but it's not unprecedented. And one can certainly argue that by not taking an advocacy position for a charge and presenting only evidence that supported it, that MuCulloch was certainly making an indictment much less likely. (That would seem quite logical to me.)
But all of that still doesn't equate to the Grand Jury being "irrelevant". Once again, this wasn't a normal case. The members of the Grand Jury weren't sequestered; they knew full well how emotionally charged this was, and could certainly have been intimidated out of fear for violence in the community, (or even for their own personal safety) into voting for an indictment, even though the DA wasn't taking an advocacy position for it. They certainly had the power to do so. (I think it's to their credit that they didn't allow this to effect their judgment)
The unusual nature of this case is also why the complete transcripts of the Grand Jury proceedings have been released, something else that isn't usually done.
Here's a
NY Times article with some opposing views from legal experts on the way McCulloch decided to handle this:
A day after the St. Louis County prosecutor took the rare step of releasing thousands of pages of grand jury testimony in the Michael Brown case, his move prompted a sharp debate among legal experts, some of whom charged that what looked like the prosecutor’s transparency and neutrality cloaked his real goal — to ensure that no indictment of the police officer occurred.
“It looks like he wanted to create the appearance that there had been a public trial when in fact there hadn’t been,” Noah Feldman, who teaches constitutional law at Harvard, said by telephone on Tuesday. The impression that was left, Mr. Feldman added, “was that the prosecutor didn’t want an indictment — and didn’t want to blamed for not getting one.”
Normally, a grand jury is led forcefully and selectively by a prosecutor seeking an indictment, but in this case, the prosecutor, Robert P. McCulloch, made it clear from the beginning that his office would present everything to the grand jurors, including contradictory evidence, regarding the officer who killed Mr. Brown, Darren Wilson.
And even if the grand jury declined to return an indictment, Mr. McCulloch had said, his office would take the highly unusual step of releasing publicly everything that had been presented in the confidential grand jury proceedings.
“That is as transparent as we can get, short of putting a pool TV camera in here, and that’s not going to happen,” Mr. McCulloch told the grand jurors when he met with them at the start of their inquiry on Aug. 20, according to the transcript of the proceeding.
But by taking a stand of apparent neutrality, the critics argued, Mr. McCulloch was really steering the jurors away from an indictment.
On Monday, after the grand jury voted against bringing charges, Mr. McCulloch released thousands of pages of testimony as well as exhibits and photographs that the jurors had reviewed, and scholars, prosecutors and columnists began wading through them — with mixed reactions.
William Fitzpatrick, the longtime district attorney in Syracuse and president-elect of the National District Attorneys Association, said grand juries were usually asked to consider cases after the police had found probable cause to make an arrest, and in such instances, if he agreed an arrest was justified, his office would present a case in support of bringing charges.
In Mr. Brown’s death, in which no arrest of Officer Wilson had been made, “it absolutely should have been a neutral presentation,” Mr. Fitzpatrick said.
He added that under New York law, he would be prevented from releasing grand jury materials as Mr. McCullough had.
Mr. Fitzpatrick said Mr. McCulloch’s decision to release the grand jury materials, which Mr. McCullough had concluded was legal under Missouri law, “was a good decision.” And he endorsed the St. Louis County prosecutor’s approach to presenting the evidence before the grand jury.
But a critic, Jeffrey Toobin, in a post on the New Yorker website on Tuesday, suggested that Mr. McCullough’s air of neutrality was a ruse. “There is little doubt that he remained largely in control of the process; aggressive advocacy by prosecutors could have persuaded the grand jurors to vote for some kind of indictment,” Mr. Toobin wrote.
Grand jury investigations are typically kept confidential for reasons like protecting the privacy of individuals who might be under scrutiny but who are ultimately not charged, or to maintain the integrity of a continuing investigation. Mr. McCulloch’s office, in releasing the grand jury transcript, took steps to redact the names of witnesses before the document was made public.
http://www.nytimes.com/2014/11/26/us/mi ... .html?_r=0
Insurance companies sell BOPs (business owner) which cover riot damage to commercial buildings. 
