Well Logically throwing a body in water attached to rocks never works because people try it.
bodies float because of excess air in the blood and lungs,
people can be Identified by hair and teeth as well.
so just for basis, for starters
Puncture the lungs fill with water.
Pull teeth
Scalp+shave entire body (Don't forget those pesky nose hairs)
Yank Fingernails
visual confirmation is a secondary identificantion. So you'd need to mangle the face as well.
But you can still get DNA from Skin Graphins.
so now you need to at least Burn the flesh. so Fire is nessecisary.
so now you need to do
Puncture the lungs fill with water.
Pull teeth
Scalp+shave entire body (Don't forget those pesky nose hairs)
Yank Fingernails+toe nails
Fane mangle
start the corpse on fire.
Burning flesh Smells bad. so you'd need to do it somewhere that the public would not notice the smell. If you live in New Jersey, this isn't so much of a problem. The smell of Burning flesh is 50% of the air content there anyway.
outside of that your better off finding some what to chop up the corpse so it'll burn easier in chunks.
now bone marrow also carries DNA.
A Grinder/Woodchipper is needed to Grind it up into Dust.
Take the remaining dust and throw it off a large bridge into a body of water.
there problem solved.
don't forget the grind the teeth as well.
