Using Mnemonica kill the trooper who used it : "After the transfer is complete, the original user, now in Dead state, is removed from play."
But ijw said that you have to reveal if the G:Mnemonica model was the lieutenant. Which makes the guessing irrelevant - you know the skill has been transferred. If you Isolated a G:Mnemonica lieutenant and then killed it in the same turn you'd know the new trooper was the lieutenant - the only ambiguous situation I can see is if they are killed in a later turn after Loss of Lieutenant, and that ambiguity is only that they might not transfer their WIP to the replacement lieutenant just to keep you guessing. From reading the skill, this line makes it look like you are not intended to reveal the G:Mnemonica was the lieutenant at all: You must identify the figure or Marker that acts as host, but not whether the Lieutenant Special Skill is transferred—that is Private Information—.
Right. I was just answering the question of why you might have a non-Lieutenant aspect in the first place.