Claims of non-citizen non-resident employees of the United States as specified in § 25.2(a), if otherwise compensable, shall be approved only upon evidence of the following nature without regard to the date of injury or death for which the claim is made:
(a) Appropriate certification by the Federal employing establishment; or
(b) An armed service's casualty or medical record; or
(c) Verification of the employment and casualty by Department of Defense personnel; or
(d) Recommendation of an armed service's “Claim Service” based on investigations conducted by it.