When an employee who has sustained disability compensable as a scheduled or unscheduled permanent disability less than total, and who has filed a valid claim in his lifetime, dies from causes other than the injury or occupational disease before the expiration of the compensable period specified, the income benefits specified and unpaid at the employee's death, whether or not accrued or due at the time of his death, shall be paid, under an award made before or after such death, to and for the benefit of the persons within the classes at the time of death and in the proportions and upon the conditions specified in this subsection and in the order named:
Idaho Code § 72-431