I seriously doubt if a Mob “hit team” would have used a knife.
Takes to long. Too messy. Too much chance of something going wrong.
Shot to the head would be more like it.
A knife to take the head off? That is the mark to tell others STFU. There was no sound, no reports of a scuffle. If someone is delivering drugs, or moolah, or the reverse. People are unguarded.