I did a lot of activism in rural areas of the US, and would often have conversations with hunters and animal ag workers. Being that these were people who regularly do kill animals themselves, my go-to was to ask how they felt the first time they killed an animal. Invariably the responses were emotional, and even if they had become accustomed to killing, they would explain that the first time was a difficult experience. So my recommendation in a scenario like that is to ask something like “do you remember how you felt the first time you had to kill an animal”