(a) The amount of group life coverages and group accidental death and dismemberment coverages in force for a participant on the date the participant dies shall be paid, on the establishment of a valid claim, to a person surviving the death in the following order of precedence:
(1) to the beneficiary designated by the participant in a signed and witnessed writing received before death by the appropriate office of the applicable system; or
(2) if a beneficiary is not designated under Subdivision (1), in accordance with the death benefit provisions of Subtitle C, Title 8, Government Code.
(b) For purposes of Subsection (a)(1), a designation, change, or cancellation of a beneficiary in a document, including a will, that is not executed and filed in the manner described by that subsection is not valid.