Grand jury investigations are for serious charges in Massachusetts. In order for a case to be indicted or charged in Superior Court, it must go through the grand Jury process. The grand jury is essentially a secretive presentation of the facts in a criminal case being heard and reviewed by people serving jury duty. A grand jury consist of 23 jurors who will decide if there is enough evidence to bring an indictment or a criminal charge against a defendant. The grand jury does not consider guilt or punishment.
The prosecutor is tasked with bringing forward enough evidence to charge a defendant. In order to gather the evidence, the prosecutor may use the grand jury as an investigatory tool. The grand jury investigation allows a prosecutor to subpoena people and records to the grand jury. If the prosecutor believes that a person may be helpful to prove that a crime existed, the prosecutor may subpoena that individual to testify in front of the grand jury.
If you receive a grand jury subpoena it can be a very dangerous thing. When testifying in front of the grand jury you are required to swear under oath that you will tell the truth and nothing but the truth. If you lie in front of the grand jury you can be charged yourself with perjury which is a serious felony in Massachusetts.
Another reason why testifying in front of the grand jury may be dangerous is if you yourself is part of the crime. The prosecutor does not need to tell a witness that they may also be a target of the investigation. As a result, by you testifying, you may actually be helping the prosecution bring charges against you. You may have be helping the prosecution in convicting you and sending you to jail.
There are hundreds if not thousands of people that testify in front of the grand jury all the time without any issues. Most witnesses would agree that it is not the most comfortable task, but in most cases it won't lead to any criminal consequences. However, if you do have any criminal issues or may be involved with any crime, the last thing you want to do is to testify as a witness in the grand jury.