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.