What are the symptoms of poisoning in a chicken/rooster?

[weesy68]

We came home from work today to find our rooster dead. We have a neighbor who HATES him with a passion, we suspect she may have poisoned him as he has no visible injuries. He was a big healthy nine month old boy in his prime. We found him on his back with his neck twisted almost in an S bend, but not broken, as if he died in great pain. What would poisoning do to a bird?

 

[BamaSilkies]

It could be. If you have the nerve to do it you could open the crop to if you can see anything obvious like rat poison pellets. It is possible that it was just a heart attack though. It happens and it is sudden like that.