The grand jurors listen to evidence and decide whether charges should be brought against an individual that’s if they decide to indict someone.
“In the United States the prosecutor presents evidence at a hearing before a grand jury, which may or may not return an indictment for trial” (Prosecutor. (2014). Encyclopædia Britannica,)
If the grand jury decides to indict it returns as a "true bill.", but if not the grand jury returns a "no bill". Although a jury can return a no bill it doesn’t mean that the case is closed in some cases. Prosecutors can return to the same grand jury with more evidence, present the same evidence to a second grand jury, but in some jurisdictions that give prosecutors a choice they can bypass the grand jury and file a criminal complaint.
When a grand jury is presented with evidence the grand jury determines whether there is probable cause to believe the person has committed a crime and should be put on trial. If the grand jury determines there is enough evidence, an indictment will be issued against the defendant. The proceedings are not open to the public and the defendant and their attorney do not have the right to appear before the grand