I've read of many cases like this, but the always involved elderly people. Sometimes cancer, sometimes vegetative states, sometimes Alzheimers. At least one shooting took place in a hospital.
For cripes sake, why not hospice, mister? I have three or four relatives who went that route and it made things so much easier. I've got an uncle (actually a much older cousin) in his last weeks (#FuckCancer, #FuckTobacco) who thanks to hospice care is able to go pain-free while his kids get in their last visits.
Addendum: Mr. Chumbly is three years younger than me but looks ten years older. He's had a hard life and/or been through hell during his wife's illness.