Me. Rev. Stat. tit. 23, § 6073

The Commissioner of Public Safety may commission and rescind the commissions of all railroad police officers in the State. The commissioner may commission and rescind the commissions of railroad police officers recommended and appointed by the chief police officer, or in his absence the chief operating officer of any railroad located wholly or partially within the State. Railroad police officers shall be qualified persons as defined in section 6072, subsection 1, and are subject to the existing rules of the commissioner. Nothing contained in this Act may relieve any railroad from any civil liability for acts of a policeman in exercising or attempting to exercise the powers conferred by this Act.