I really get upset reading about dogs killing people. Very depressing. This poor woman and her family.
Having said that, I'm still a firm believer in all dogs can and most likely will at some point bite, even well trained ones. Kill is a bit further, I haven't really gotten to deep in that subject.
I've had several friends that were attacked as children. One was just a young boy playing on a beach, a dog runs up from somewhere it was out of sight before, and attacked him. No one knows why.
Parents raised all types of dogs, so I've always been around them. My dearest passed last year, she was getting snappy but it was because she was sick. The older a dog gets, the more "snappy" it gets. Sometimes they are in pain, could be arthritis, could be cancer, could be spleen issues, you never know. Could be they have a headache. If they feel badly, they may bite.
A neighbor had a Lhasa Apso. He was a really cute little white ball of fur and moustache. She was in her 60's and had many dogs in her life. She always said, "Well, he's never bit, but that doesn't mean he won't. He is a dog, dogs bite." She was right. We had him outside with us one day when a known neighbor came up and bent over to pet him. He bit him. No one knows why, other than the dog was being grumpy that day, so she had him out for a minute or two longer than usual so he could soak up the sun and all of our attention.
In short, a dog is a dog, even well trained. If something triggers for the dog, then it does, even if it is the best dog in the world before. It is the owner's responsibility and liability. So, when my beloved dog passed, I decided to get no more. Seen too many lawsuits and dogs put down when they were being provoked, not just when the bit out of the blue. Plus I live in apartments, not many allow any kind of dog anymore. I sure do miss having a furry friend, but it is best since I work all day and do not have many hours to devote to loving, training, spending play time, energy time. That is the best decision I can make for any other pet that really needs a good and responsible home.