maybe [C} = Classified emails before [D] = HRC raw vid drop.
The emails as a precursor?
NSA and other cyber units have state of the art data recovery techniques.
Basically when you delete something, you give permission to the machine to write on top of it.
If you know how the memory is managed, you can come up with some elaborate methods of recovery.
also you can recover data based on fragments of files.
Some of these methods entered the civilian market, e.g the Israeli Cellebrite company, via military cyber program graduates who retired from service.