About two weeks ago, I called NSC customer service center and got an opportunity talking to the representative. The next day I recieved this letter.
Online message doesn't show anything about background investigation. 
回复:BTW, when did you receive the letter from USCIS?
所有跟帖:
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                    keep calling them.
                     -xiaoshagua- 
                    ♂                    
                        
                    
                                                            
                    
                    
                                        
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                        12/01/2006 postreply
                                                12:26:40