Daisy, I think it is a well known fact that harming animals is a precursor to harming adults. Although I don't think that it is a given that someone harming animals will automatically harm adults.

When I was a young child (oh, my, so very long ago) there was a boy in my neighborhood that hung his cat. He wanted to see how a lasso worked. He went on from there to killing squirrels so he could disect them. He was an odd sort, and eventually got caught by his family.

He ended up being a nice young man, a gentle sort. He started out nasty, tho. Something or someone must have intervened and changed his life around.

I heard or read recently about another murderer that started out by tying the tales of two cats together and watch them kill each other. I don't remember the specifics, but in this case he did go on to murder humans.

All of this to say, the harming of animals is usually a sign that someone does have a mental illness and perhaps, if found when they are young, perhaps they can be helped. The harming of animals should not be ignored.