Mass. Gen. Laws ch. 22C § 65
The colonel may, upon petition of the board of trustees of the Middlesex County Sanatorium, appoint as special state police officers employees of said institution, who shall have the same power to make arrests as regular police officers for any criminal offense committed in or upon lands, or structures owned, used or occupied by said sanatorium. Such special state police officers shall be sworn before a justice of the peace or notary public who shall make a return thereof to the department upon a form provided by said department. Upon receipt of said return, the department shall issue a license to each person designated to act as a special state police officer, and such license shall, in any court of the commonwealth, be competent evidence of the validity of the appointment of the person named therein and of his authority to act as such special state police officer. A special state police officer shall hold his office until his license expires or is revoked, by the colonel, or until the petitioner files a notice with the department that the services of such officer are no longer required. The colonel may provide that the license and any renewal thereof shall expire on the anniversary of the birth of the person named therein not less than one nor more than two years following the date of issue. Such special state police officer shall report to the colonel as to his official acts at such times and in such manner as the colonel may require. Such special state police officer shall serve without pay, except his regular compensation as an employee of said institution, and shall receive no fees for services or return of any criminal process.
Mass. Gen. Laws ch. 22C, § 65