Investment of escrow funds.

Funds held in escrow by the escrow agent under an escrow agreement entered into pursuant to s. 132.41 may be held uninvested or may be invested only in direct obligations of the United States of America or in obligations the principal of and interest on which are unconditionally guaranteed by the United States of America, which obligations shall mature or be subject to redemption at the option of the holder thereof in such amounts and on such dates as funds will be required to make payments in accordance with the refunding financial plan. Any moneys remaining in the custody of the escrow agent after the full satisfaction of all obligations to be paid from moneys held in escrow by the escrow agent under the escrow agreement shall be returned to the unit and, if any general obligation refunding bonds remain outstanding, shall be applied by the unit to the payment of the principal of or interest on such general obligation refunding bonds.