Chris, thanks for the followup. You could use custodian as the source location for identification, for example name of sub folder containing the users doc's and PST. Also it would be good to add the ability to tag evidence containers inside Intella with a custodian name. I would add this as another field rather than a standard tag so you can easily filter by custodian in the facet without having to use the standard tagging method.
"Would you want to see the raw amount, the deduplicated amount, or perhaps both?" I would prefer both if possible.
Cheers
Andy J