Mass. Gen. Laws ch. 127 § 156
The governor and council shall, upon receiving such notice, examine the case of such prisoner; and if it appears by his own admission or by evidence that he has violated the condition of his pardon, the governor, with the advice and consent of the council, shall order him to be remanded and confined for the unexpired term of his sentence, said confinement, if the prisoner is under any other sentence of imprisonment at the time of said order, to begin upon the expiration of such sentence. In computing the period of his confinement, the time between the conditional pardon and subsequent arrest shall not be taken to be part of the term of his sentence. If it appears to the governor and council that he has not broken the conditions of his conditional pardon, he shall be discharged.
Mass. Gen. Laws ch. 127, § 156