OMG, that's terrible! If anyone ever beheaded my bunny, I'd shoot them for sure. Also, a co-sign on reporting the incident to the police. Like labeachgrl said, cruelty to animals is one of the first signs of sociopathic behavior. If the police catch the person, maybe the neighborhood won't have a budding serial killer on their hands.
Well I and about 15 other people tried to convince my friend to call the police and file a report. But she refuses to. She listened instead to her ONE friend who said it was probably just an animal because her cats behead chipmunks all the time. Whatever, most cats are smaller than New Zealand white rabbits, so obviously a cat could not have done it. And I just don't believe that any animal would have done it that cleanly, plus jumped over the fence with the head.
So whatever. If it were me, I'd file a report because of the whole budding serial killer possibility, but if she doesn't want to then there's nothing more I can do.