Yeah, killing four people with a knife would require one who is pretty nifty with a knife-—but possible. But let’s wait for the autopsies. One of my guesses is a party time bad coke dose, knocked everybody out, and the dealer didn’t want any survivors to complain about his stuff? No apparent calls for help is curious and suggests a knockout event.
A machete wouldn’t require much skill to use , pretty effective edged weapon.
You could hack four people to death very easily.
You should be a detective! Excellent reasoning