Mass. Gen. Laws ch. 6 § 178P
Whenever a police officer has probable cause to believe that a sex offender has failed to comply with the registration requirements of sections 178C to 178P, inclusive, such officer shall have the right to arrest such sex offender without a warrant and to keep such sex offender in custody.
Whenever a police officer, district attorney or agent, employee or representative of the executive office of health and human services has information indicating that a sex offender is at risk to reoffend, the police department, district attorney or, to the extent permitted by federal law, the executive office of health and human services agent, employee or representative shall forward that information to the board; but a police department or district attorney shall not forward information to the board that the police department or district attorney believes will compromise an ongoing investigation. The board, after consulting the executive office of health and human services, shall adopt regulations to provide specific guidance concerning the type and location of information that might indicate that a sex offender is at risk to reoffend and the circumstances that require disclosure.
Mass. Gen. Laws ch. 6, § 178P