in my area, pets are property. Although it is illegal to be cruel and yes shooting them for no good reason.
Before you all go and start up in arms... in our area it would not be uncommon for shooting an animal in the head to put it out of it's misery if the animal is beyond help and suffering, not that I would ever do it, I'm just stating what is not uncommon in my area.
I had a neighbor use a pellet gun on my cat and since the only thing I witnessed was, THE SHOT, the neighbor running after my cat with the pellet gun in his hand, the police said that since I did not see him pull the trigger then there was nothing I could do to prove he had done it. I could have taken my cat in for xrays but unfortunately at the time I had my electricity already shut off in my house and was almost unable to feed me, my 2 kids and the pets that I had. So, I could not afford to take my cat in for xrays. I know darn good and well he shot my cat up the wazoo out of pure and simple cruelty. I know this because I've seen another person do that to a cat when I was a child. This does not show any outward harm but of course rips them apart inside so they essentually bleed to death from the inside. That is extremely cruel. My cat ran off and even though I was on the phone trying to see if I could get help, I got NONE, absolutely none, none from the police, none from vets unless I could pay, nothing. She disapeared and I never saw her again. That is one of the kitties that I truely am
over knowing how she must have passed.
ANYWAY, unless you personally can prove it, there really isn't anything that could be done. If the people have any kind of property and have any kind of heavy equipment, there is nothing to say that they can't kill what ever they want and bury it deep. If you live in an area like I do with lots and lots of hills and forest land, they can kill what ever they want and take it up and dump it off in the woods, it would be taken off by scavangers almost instantly.
So, as unfortunate as it may seem and as heartbreaking and not very positive suggestions or help, it is the way the law works. Animals are property, not family members by law. You can call your local animal control agency, Animal shelters, and law enforcement agencies to find out what is the law in your area. I have done that to find out information in the past.
You can see if printing the forums they are writing it on and taking it to authorities to see if anything can be done also. But, if they are not in your area (different parts of the world have way different laws), I honestly don't know what your recourse would be.
I hope they see that what they are contemplating is cruel and have a change of heart.