ELI5: Are Forensic Pathologists able to know if a person's body was mutilated while they're still alive or if their body was mutilated after their death?

I once read a comment on a Disturbed Reality video which states that some "not so evil" cartel sicarios prefer to kill the victim first by shooting them in the head (or smth like that) before mutilating their bodies (perhaps a way to ease their conscience), as opposed to some of the gory cartel execution videos we see in the internet where they are being tortured by mutilation, castration, etc. while they're still alive.

Edit: This question of mine must've put me under the authorities' watchlist but nonetheless, very big thanks to those who answered. Also, just to be clear, to those having doubts if I'm planning on killing somebody, my answer is a big fucking NO. I'm just a random teenager here in the internet who's curious about these morbid stuff, but still, I know my limitations, and I 110% do not condone these acts being done to people.