A "Widow's Prior Service Annuity" shall be credited for the widow of a male present employee for service prior to the effective date in accordance with "The 1925 Act" and this Article, payable from and after the death of the employee.
The amount so credited shall be improved by interest at the effective rate during the time the employee is in the service or until the employee attains age 65 or withdraws from the service, whichever event first occurs.
40 ILCS 5/9-136