Me. Rev. Stat. tit. 34-B, § 3869

If any patient committed under section 3864 leaves the grounds of the psychiatric hospital without authorization of the chief administrative officer of the psychiatric hospital or the chief administrative officer's designee, or refuses to return to the psychiatric hospital from a community pass when requested to do so by the chief administrative officer or the chief administrative officer's designee, law enforcement personnel of the State or of any of its subdivisions may, upon request of the chief administrative officer or the chief administrative officer's designee, assist in the return of the patient to the psychiatric hospital.