No idea why I am actually replying to this but here goes.
As a butcher (20+ years) I know anatomy and how to break it down. Yes I know it was a cow or pig or lamb etc but the same principle works. When I worked in a then big named butchers in the late 90s we had the bone man come round every Monday morning. He came to take away our big blue barrels of off cuts, bones, crap that we didn't use during the previous week. This barrel was kept in the freezer whilst we filled it over 7 days. We chatted to him once about what happens to this barrel once it leaves our shop. He just said it gets thawed out and dumped in a incinerator. No idea where but it was never checked for anything that could have been used for dog food or that sort of thing.
So. Dead body on my butchers block. 10 mins to cut into primals, head, arms, legs, feet etc. Organs, such as heart, livers, kidneys etc can be taken out and minced and dumped into the barrel and classed as 'gone off offal'. The legs, arms etc can be boned and boning a human male 6ft and 12 stone in weight would probably take me 15 minutes. The skin is softer than a pigs so would go through the mincer quite easily just like the meat on the body. Bone would be sawn in chunks and put in the barrels, not all in the same barrel but separated over 3 or 4. Teeth and other bits that wont mince or give the game away would be taken from the shop and juts put in a bin in the center of town some where. A full set of teeth cleaned and in a plastic bag wont cause any unwanted attention, small and compact. So easy to dispose.
The head is the hardest part. Guess it's a case of smashing the skull in and chucking the bone fragments into the barrels.