I was playing Case 1 earlier, and I believe that Edgeworth said this:
"This case was handled by the high prosecutor before me who occupied this room."

The file in question is

and the prosecutor in that case was

This led me to only one conclusion:

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Yeah, it sort of belongs to "Obvious things that you didn't notice right away" thread, because it isn't speculation. It is clearly, yet so unnoticeably stated. It was just poorly executed, to the point many miss that fact.

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