Upon the receipt of proper proofs of the death of a member in service there shall be paid to his estate or to such person having an insurable interest in his life as he shall have nominated by written designation duly executed and filed with the board of trustees

(1) His accumulated contributions; and

(2) If the member has had one or more years of creditable service and no pension is payable under the provisions of section 86.093, in addition thereto an amount equal to fifty percent of the compensation earnable by him during the year immediately preceding his death.