Too much of an over dose of Midazolam, aka Versed can kill you with no pain.
Millions of us have had Versed pre op or pre procedure. Most of us had no recall of the surgery or procedure and went home with a driver for the rest of the day. It is painless and eliminates any memory of what happened, (not necessary to kill a killer).
Midazolam doesn’t work on some people, for example me. Still remember being awake at the start of my hernia operation. Docs thought I was out. I wasn’t but could not move or speak. Fortunately I also could not feel any pain, just some pressure.
That said, I could not care less if the scumbag suffered horrible pain.