No murder weapon?

It's just bad writing and bad movie at all.

I think, given enough time, it would be entirely possible to mutilate someone beyond recognition with your teeth and fingernails, just tearing off smallish chunks of flesh at a time.


credo quia absurdum est

It's not bad writing & it most certainly is not a bad movie. I just read a whole line up of mindless smearing based on a lack of imagination from the OP & others. LOL! Wow. Somebody saying bad writing just sounds like a stock answer to make out as if they really know what they're talking about. "I'll just say bad writing & that'll make me sound intelligent."

I'd say most killers aren't crazy enough to kill children let alone mutilate them, yet it does happen. It was to make the audience aware of how insane this guy is & it really isn't impossible for an adult (who would have to be completely evil, heartless & insane) to do what he did. It doesn't happen very often because most killers aren't insane & want to get away with their crimes. This guy was so crazy & sick that he actually took the time to dismember 2 little children, not worrying about getting caught & was even mentally messing with the babysitter while he was doing it. Having this image be brought through dialog, instead of what has now become common, predictable & unexciting (showing it,) is brilliant. Today we would get the flashback shots with the voice over and a couple of flashes thrown in with punctuating crashing noises in between edits for good measure. How many times have we seen that today? Creating it with just the dialog is far more effective & more focused on the story instead of distracting, boring & unnecessary effects that really don't amount to much anyway. Sorry & I beg to differ. This movie is far better than the remake & just as good, if not better, than most thrillers today!

Slavoz Zizek has some wonderful comments on this film in his book "Enjoy your symptom!" and if we continue his chain of thoughts - "riff" - we'd see that the fact that the killer used his bare hands is a further way of speaking of the "unspeakable" horror of his actions.
We are dealing with a tremendous crime, a crime born out of the human condition itself ("look at what we produce!").
It's exaggerated - for sure - for for an affect, it tells us that this "unknown" (which, remember, "came from within the house") was a demoniacal force of pure evil.
"The evil inside", if you will, who needs to weapons, only rage and desire (or a negative desire) to fully desecrate its environ.
Taken this way, by being so extreme, so over-the-top, by pushing the envelope, it becomes symbolic, or you could say, to truly (re-)present how heinous this crime is, it had to be done without weapons... Only that way does it imply how it would appear within the mind... (There is a blurring of imagination and reality in these kinds of films). There is no mediator between the rage and its affect.
A pure act.