There are two different kinds of juries that may be important to your federal criminal case. The jury is known as the petit jury (or simply the jury) is the one that will be present at your trial and decide whether you are guilty or not guilty of the crime(s) with which you have been charged. However, before that jury can get to work, you must have been formally charged with a crime. If that crime is serious then your formal charges may come in the form of a grand jury indictment.
What is a Grand Jury and What Can It Do?
You might not know that you are the subject of a grand jury investigation until that investigation is complete. Generally, grand juries meet in secret. Jurors serve terms of six to 18 months (or longer) and typically work as grand jurors for several days a month. While serving on a grand jury, grand jurors listen to testimony from prosecutors to determine if there is probable cause that you committed a federal crime. You will most likely not have the chance to defend yourself before the grand jury. If the prosecutor convinces the grand jury that there is probable cause that you committed a crime then an indictment will be issued.