A grand jury formally accuses a defendant when it hands down an indictment. The grand jury process is limited. Only the prosecuting attorney presents information.
Prosecutors do not submit their entire case. They only show the jury enough information to indicate that someone mostly likely committed a crime. The evidence comes in many forms, such as testimony, documents, photos and scientific test results. If the grand jury agrees that the evidence shown supports the prosecutor's viewpoint, they will indict the accused. However, if the jury does not believe that the evidence provides sufficient proof for indictment, they return a "no bill" or "bill of ignoramus." The prosecutor drops the case or gathers more evidence to try again.