And now he should kill all 3.
There's a chance they could get loose while returning.
What's worse, is that some idiot might start arguing that they need those "heroes".
Psychopathology isn't curable, and their society doesn't look like it has the resources to handle 3 persons like that.
Just crush their heads, and burn the brains, so you don't leave anything to resurrect. Preferably strew important parts far away from each other, and in flowing water.
Also, perform an exorcism.
No half measures with true monsters.