Any trustee holding trust funds may invest the same in bonds or other securities issued by this state, making a true return of the price paid and time of purchase. The investments shall be free from taxation as long as they are held for the trust estate. Trustees are also authorized to invest trust funds in direct and general obligations of the United States government, obligations unconditionally guaranteed by the United States government, or obligations of agencies of the United States government issued by the Federal Land Bank, Federal Home Loan Bank, Federal Intermediate Credit Bank, and Central Bank for Cooperatives. No person, firm, corporation, or association shall be liable to account for a greater rate of interest than the amount actually received on the investment. Any other investments of trust funds shall be made under an order of the superior court or shall be at the risk of the trustee. Deposits of funds at interest in any chartered state or national bank or trust company located in this state and insured by the Federal Deposit Insurance Corporation shall be deemed investments; and the deposits are authorized as legal investments, to the extent that the deposits are insured by the Federal Deposit Insurance Corporation, without any order or authority from any court.