All that's needed for this is knowledge and the right image in mind. So that's how the Aurors found the Goyle family sans the youngest, nailed to their wall in order of youngest to oldest each of them having died of organ failure or shock as I transfigured their organs to useless lumps comprised of various materials one might perceive as dirty in order of the least important organ to the most, leaving the brain intact in a solution I designed to keep them alive without organs or blood, I left them with no organs and mud for blood with a functioning brain nailed to their walls, the Aurors would discover them on their walls like that still alive and very much in pain and when the abject horror of that sight settles down and they try to reverse the transfigurations the charm i placed on the brain that responds to finite activates by flooding the cranium with a lovely little mixture of hydrogen peroxide and sulfuric acid called Piranha solution, dissolving their brains in real time as the Aurors can only watch and even if they did stop it halfway through a Death Eater comatose missing half a brain isn't exactly a threat.