20 C.F.R. § 30.113

(a) All written medical documentation, contemporaneous records, and other records or documents submitted by an employee or his or her survivor to prove any criteria provided for in these regulations must be legible. OWCP will accept photocopies, certified copies, and original documents and records.

(b) To establish eligibility, the employee or his or her survivor may be required to provide, where appropriate, additional contemporaneous records to the extent they exist or an authorization to release additional contemporaneous records or a statement by the custodian(s) of the record(s) certifying that the requested record(s) no longer exist. Nothing in this section shall be construed to limit OWCP's ability to require additional documentation.

(c) If a claimant submits a certified statement, by a person with knowledge of the facts, that the medical records containing a diagnosis and date of diagnosis of a covered medical condition no longer exist, then OWCP may consider other evidence to establish a diagnosis and date of diagnosis of a covered medical condition. However, OWCP will evaluate the probative value of such other evidence to determine whether it is sufficient proof of a covered medical condition.