Mass. Gen. Laws ch. 12 § 25
Money to be used for the necessary expenses to be incurred by officers, under the direction of a district attorney, in going outside of the commonwealth for the purpose of searching for, or bringing back for trial, persons under indictment in any county in the district of said district attorney shall be advanced by the treasurer of the commonwealth, upon the presentation of a certificate signed by the district attorney and approved in the manner provided in the preceding section for approving bills incurred by district attorneys. After their return, such officers shall account for such money by filing with the treasurer itemized vouchers duly sworn to, approved by the district attorney and also approved in the manner provided in the preceding section for approving bills incurred by district attorneys. Such vouchers shall show the necessary expenses so incurred, and the difference between the amount advanced as aforesaid and the amount of the vouchers so approved shall be paid to the treasurer within thirty days after such return.
Mass. Gen. Laws ch. 12, § 25