It's fake. Albeit a good fake, it is still fake.
(Inquire later if you are interested in why. I will check this comment out later.)

I am quite certain it's supposed to resemble repeated blunt-force violence, or a pickaxe to the mouth, in the same repeated manner of application of blunt force.

I'm not a medical examiner.. but id say it looks like a large calibur bullet under the chin. or maybe even a shotgun suicide ...