I recently got a Request For Evidence letter from USCIS Service Center for my EB-1B application, which requested the detailed documents of my previous research achievements in my home country many years ago, and also said my case could be denied if I can not provide the required evidence. It is very difficult for me to obtain these documents. I am really confused for the meaning of the Request For Evidence letter.  

An USCIS adjudicator may issue a Request For Evidence (RFE) on cases that were clearly not approvable. The issuance of RFEs in these cases resulted in delays in the processing time. On the other hand, many cases could be approved if the applicants had been given the opportunity to provide additional information in response to the RFEs.

An EB1 application case may be denied if it is clearly not approvable. These are cases where basic regulatory requirements are missing. This includes cases where an applicant is categorically ineligible to receive an immigration benefit. USCIS also recognized that sometimes the adjudicators request full range of information when only a small amount is needed to make a final decision, so it wastes examination resources through the review of unnecessary, duplicative, or irrelevant documents.