That is just horrible..... Stories like that is why i keep my cat indoors. I've had cats that have dissapeared because of their wandering.... I've also had a cat attacked within my own home so they are not safe even there 100%
(Dog actually broke through my screen door and mauled my 18 year old cat)
But....then there are the sickos out there who do that s*** on purpose. That's what really ticks me off....
My mom's neighboor is not too fond of the poop in her garden but mom's cats keep the squirls out of her tomatos so it's all good....
Plus... i get called over to rid her flowerbed of cat poop :S LoL
I am very sorry to hear of your sisters cat and i hope he/she can pull through. (kitty and her)
May i ask what area she lives in?? Scar/Birch?