Thats kinda cringe ngl.
Rehabilitation is a much more effective alternative to murder which can mentally break down a person and cause severe trauma and mental disorders. Instead have you considered psychological torture?
I studied it and it seems like a fun job for sadists.
Apparently Russia had these rooms with muddy knee deep water in a 1x2 meter vertical space for claustrophobia and leeches with no light and they would only bring raw meat as food using 10000 lumens to give them a fear of light until they would break down. Scary stuff.