If a deer hunter killed these beagles, he can personally take responsibility with all the other slob hunters that contribute to what will be the end (prohibition) of ALL hunting someday.
Chances are these beagles had collars. And chances are, a deer hunter would be smart enough to know the rabbit hunter would be along shortly, and he could talk to rabbit hunter about the problem of them chasing deer.
Before you think I am an AR fanatic -- I am as PRO hunting as one can get, and I hunt. Even though the slob hunter may be legally safe, his attitude sucks, and gives lots of ammunition to the non-hunting public, as well as AR fanatics.
Here in the state where I live there is a deer hunting website I used to frequent. There is a core group in there who brag about shooting people's dogs if they even WALK under (around) their treestand (not chasing deer). If my dog ever disappears I will go on there and find the perpetrator, because idiots like this are too stupid not to brag about it.
I'd be willing to bet the beagles were on a rabbit, and IF a deer hunter killed them he is not what I would call an ethical hunter.
Of course, there could be more to the story, like prior conflicts with these hunters, etc. But shooting these dogs was an ignorant thing to do.
And yeah, I've met guys like you mentioned too. They suck and are a shame upon all of us who hunt. And if they do that in Pennsylvania and get caught shooting a dog that's just walking around the woods not chasing deer, they can be prosecuted under the Criminal Code.