We will never know what it actually was as they did not test for what the exact toxin was.He was so far gone by the time we managed to get to the emergency vet, that we all knew his chances were slim.
Sad to say there are those around here that think such cruelty is funny.
That is very sad. Like qq said, though, it was probably not intended for the cat. My next-door neighbor tried using poison when a groundhog was ravaging his garden then called the city when that didn't work. The city guy chewed him out, both because it's illegal and because pets might be hurt. My neighbor wasn't thinking of pets at all and regretted using the poison after the city guy made him engage his brain.