Evidence
Primary source
Verbatim text below is from the Electronic Code of Federal Regulations (eCFR), a public-domain U.S. government work. Always verify the current version with the eCFR before relying on it for any legal matter.
Full Text
(a) Standard Form 2806 (Individual Retirement Record) is the basic record for action on all claims for annuity or refund, and those pertaining to deceased employees, deceased Members, or deceased annuitants.
(b) When the records of the department or agency concerned are lost, destroyed, or incomplete, the department or agency shall request the General Accounting Office, through OPM, to furnish the data that it considers necessary for a proper determination of the rights of the claimant. When an official record cannot develop the required information, the department, agency, or OPM should request inferior or secondary evidence which is then admissible.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.