The goal was to find out if the minion was killed at then end of the monologue, since the party has been invested in thinking that the minion was the BBEG.
Well that didn’t go as planned.
Edit: Apparently posting images is down at the moment, so had to troubleshoot.
Wow, I wish I had thought of that.
Great options. Alternatively, I would have had the BBEG just keep monologuing to the corpse without breaking stride. Maybe only realize the kill at the end of the speech as if the minions death was both accidental and irrelevant. (“Do you understand now?! … Oh. Yuck. Somebody clean this up!”)