OP is mistaken - including the comma or not implies nothing whatsoever about whether there might be other investigators also called Ace Sleuth, based in other locations.
The general tendency is to use less commas over recent decades, and they're certainly not grammatically required in this specific context, so ordinarily I'd say don't bother with it.
But since OP is acting as court recorder, I suggest it's probably better to use a comma - if only because it forces the reader to pause, imparting slightly more "gravitas" to the text. Which is only right and proper for text with strong legal associations.
If Ace Sleuth had left an unusually long pause after his name, OP could indicate this by ellipsis (three dots), but I think it would be unrealistic to attempt to faithfully reflect normal pauses in speech using commas. The reader would just end up confused as to which commas reflected the actual intonation, and which were grammatically required (or simply added to improve legibility).