You don’t seem to understand the difference between “investigate” and “indict.”
Yes, a grand jury can investigate based on tips, rumors, or personal knowledge, but there must be convincing evidence that a crime was committed before a grand jury will actually indict (i.e. charge or accuse) someone.
I see no evidence connecting Obamao to Wikileaks in what you provided that would warrant a grand jury investigation, much less prompt an indictment.
You haven’t a clue about the law, the Burden of Proof before a Grand Jury or the information required for an indictment.
http://standupamericaus.com/our-privilege-our-right-and-our-duty-civilian-grand-jury:33320