All,
...in practice, a grand jury rarely acts in a manner contrary to the wishes of the prosecutor. Judge Sol Wachtler, the former Chief Judge of New York State, was quoted as saying that a prosecutor could persuade a grand jury to "indict a ham sandwich."
http://en.wikipedia.org/wiki/Grand_jury
My lawyer told me the "ham sandwich" line when I asked what are the chances of me being indicted.
I agree that most who are plea are usually guilty of something, but there are times where it is not so clear. What happened to me was definitely one of those times. It is not murder or even embezzlement where either "you did it or didn't". This was "is what we did illegal"?