Mass. Gen. Laws ch. 32 § 46
The state board of retirement upon the recommendation of the commissioner of correction may retire from active service and place upon a pension roll any officer of the Massachusetts correctional institutions or any jail or house of correction, or any person employed to instruct the prisoners in any Massachusetts correctional institution, as provided in section fifty-two of chapter one hundred and twenty-seven, or any other employee of the Massachusetts state correctional institutions, who has attained the age of sixty-five and has been employed in prison service in the commonwealth, with a good record for not less than twenty years; or who, without fault of his own, has become permanently disabled by injuries sustained in the performance of his duty; or who has performed faithful prison service for not less than thirty years; provided, that no officer of any jail or house of correction shall so be retired except upon the recommendation of the sheriff and county commissioners of the county, except in the county of Suffolk, where the recommendations as to the officers of the jail shall be made by the sheriff and the mayor of Boston, and, as to the officers of the house of correction, by the penal institutions commissioner and the mayor of Boston; and provided, further, that no such officer, instructor or employee shall be retired unless he began employment as such in one of the above-named institutions or the prison camp and hospital, or as an officer or instructor in one of the institutions named in section forty-seven, on or before June seventh, nineteen hundred and eleven. The word "officer", as used in this section and sections forty-seven and forty-eight, shall extend to include prison officer, correction officer and matron.
Mass. Gen. Laws ch. 32, § 46