The Grand Jury decides whether or not there is enough evidence to indict. To indict is to bring formal, criminal charges against a person for a felony. The Grand Jury does not determine guilt or innocence. The Grand Jury hears the evidence and decided if there is sufficient proof to bring charges against a person. The prosecutor will present evidence to the Grand Jury. After the prosecutor presents evidence, the Grand Jury will deliberate and decide whether to return an indictment. Nine of the twelve Grand Juror's must be in agreement to return an indictment.
Typically, the person who may be charged and the defense attorney do not provide any proof or evidence to the Grand Jury.
If your case has been referred to the Grand Jury, then the proseuctor has 60-days to present the case to the Grand Jury. If they do not meet that deadline, then speak to your attorney about filing a motion to get you out of jail or off bond conditions.