Fanaelialae
Legend
Inflict Wounds does damage by inflicting wounds. It's right in the name. You would notice that all of their skin was rotting off from necrosis.
In fairness, a generous DM might allow the player to inflict internal injuries with necrotic damage, thereby giving the appearance of no injury (assuming the absence of forensic science).
That's why the best approach would be to simply discuss it with the DM (or if you are the DM, make a ruling).