Me. Rev. Stat. tit. 35-A, § 4158

The State and all public officers, governmental units and agencies of the State, all banks, trust companies, savings banks and institutions, building and loan associations, savings and loan associations, investment companies and other persons carrying on a banking business, all insurance companies, insurance associations and other persons carrying on an insurance business, all credit unions and all executors, administrators, guardians, trustees and other fiduciaries may legally invest any sinking funds, money or other funds belonging to them or within their control in any bonds, notes or other evidences of indebtedness issued under this chapter, and the bonds, notes or other evidences of indebtedness are authorized security for any public deposits.