How Many Grand Juries Does It Take to Indict Tom DeLay?

This isn’t a joke, and it isn’t a light bulb question, it is the unfortunate reality.  According to an AP story on ABC News (here) it seems that one of the grand juries looking at a case involving Tom DeLay did not indict him. In total it looks like there were 3 grand juries and 2 issued indictments.  It is most likely that the conduct being looked at by these different grand juries was not the same conduct, so an indictment by one does not preclude a no bill by another.  Perhaps the most telling part, however, is  why was it necessary to have 3 separate grand juries regarding DeLay.  (esp)