It's wrong to kill a living being.
Jeff's dog keeps pooping on Roy's lawn and Roy is tired of it.
Roy wants to stop the dog from ruining his lawn.
Roy tells Jeff that his dog is pooping on his lawn.
Roy kills the dog while it's in the middle of pooping on his lawn.
Jeff makes sure that his dog doesn't go near Roy's lawn in the future.
Jeff sees Roy kill the dog and attacks him out of anger.