Not really. It's still largely visible from the outside. You don't want an outsider to look at the place of disposal (and it's near Marisa's shop?!) and went "Huh? Someone recently digged here?" immediately. She also left the shovel outside, big mistake.

For starter to dispose a human corpse you want to dig a hole vertically, so you disturb the least mud possible, and cover it with turf (real grass turf, no artificial turf) after buried the corpse to make it obscure.

It's exactly the kind of confidence and hubris someone whose done it before would have.