Me. Rev. Stat. tit. 34-B, § 3861-A

When a person who is hospitalized in a psychiatric hospital under the provisions of this chapter is sentenced to serve a straight term of imprisonment or a split sentence in a county jail, the chief administrative officer of the hospital shall notify the sheriff of the county jail so that, in accordance with the provisions of Title 15, section 2211‑A, the sheriff may process the person to serve the sentence while hospitalized and the person may remain in the hospital until ready for discharge.