The narcotics unit within the criminal information section shall be charged with the following duties and functions: to investigate all violations of the narcotic and harmful drug laws of the commonwealth; to arrest all violators of such laws; and to cooperate with the department of the attorney general in training personnel assigned to the narcotics unit in practices and procedures relating to the narcotic and harmful drug laws pursuant to section eleven C of chapter twelve.
Mass. Gen. Laws ch. 22C, § 40