JM 9-16.500
In the absence of some significant justification, it is generally not appropriate for a United States Attorney to identify (either by name or unnecessarily-specific description), or cause a defendant to identify, a third-party wrongdoer unless that party has been officially charged with the misconduct at issue. When referring to the uncharged third party, the use of non-generic descriptors, like a person's actual initials, is usually an unnecessarily-specific description and should not be used. See JM 9-11.130; 9-27.760.
[updated December 2014] [cited in JM 9-11.130]