Mass. Gen. Laws ch. 119 § 54
If complaint is made to any court that a child between 12 and 18 years of age is a delinquent child, said court shall examine, on oath, the complainant and the witnesses, if any, produced by him, and shall reduce the complaint to writing, and cause it to be subscribed by the complainant.
An application for such complaint submitted to the juvenile court by a police department against a child arrested for a felony offense shall be accompanied by an offense-based tracking number. The failure to include the arrestee's offense-based tracking number shall not preclude the issuance of a complaint where there is otherwise a valid application submitted by a police department against a child. If a complaint is issued based on an application for a complaint for a felony submitted by a police department against a child that did not include the child's offense-based tracking number, the prosecutor shall submit the offense-based tracking number of the child to the court to be included in the case file.
The commonwealth may proceed by complaint in juvenile court or in a juvenile session of a district court, as the case may be, or by indictment as provided by chapter two hundred and seventy-seven, if a person is alleged to have committed an offense against a law of the commonwealth while between the ages of fourteen and 18 which, if he were an adult, would be punishable by imprisonment in the state prison, and the person has previously been committed to the department of youth services, or the offense involves the infliction or threat of serious bodily harm in violation of law or the person has committed a violation of paragraph (a), (c) or (d) ofsection ten or section ten E of chapter two hundred and sixty-nine. The court shall proceed on the complaint or the indictment, as the case may be, in accordance with sections fifty-five to seventy-two, inclusive. Complaints and indictments brought against persons for such offenses, and for other criminal offenses properly joined under Massachusetts Rules of Criminal Procedure 9 (a) (1), shall be brought in accordance with the usual course and manner of criminal proceedings.
Mass. Gen. Laws ch. 119, § 54