I am sorry to hear that. Since you have posted this on autism forum, I am presuming your grandson has autism. Children with autism interact poorly with others, are often unable to understand and control their behavior, thoughts etc. Hence, they often become violent.
The first thing to do is understand what triggered this violence. Try and correlate whether similar instances created violent behavior, maybe of lower intensity such as tantrums or slapping others or hitting the wall or door etc or throwing things. If you can identify this, then it is best to avoid these triggers and find a way around them with the help of a therapist.
The child’s routine and his room things etc should be arranged in such a way that he is least frustrated. You could ask a therapist to help you out with this. Also, since this was violence at its extreme, please consult his doctor and therapist immediately to help understand why it happened and how to identify and overcome this at first signal. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.
Why did he kill the cat and how? Was it an accident or on purpose? What was his reaction? Does he feel any remorse? If he doesn't feel any remorse then you have a much bigger problem on your hands than just autism. Usually during a tantrum the person sort of "blacks out" and cannot control themselves, even if they want to. After they do feel bad about how they acted. My daughter, who has autism, always has to clean up any mess she makes during a tantrum. She knows the drill and does it willingly after she calms down. People on the spectrum have many varying personalities, just like "normal" people. They are often kind, loving, and nurturing. I cannot stress enough that autism does NOT always cause people to be violent; especially if it is correctly treated. In cases of extreme violence like this (if it was done maliciously) I am sure that there is more going on the just autism. I cannot tell you how to deal with this without more information.
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