In my novel I need to kill off one of the characters and can't figure out how. She needs to be murdered by someone else, but its a mercy killing (sort of) and the death needs to be quite peaceful and needs to look like an accident or a natural death with no clues it was murder/suicide.
Other background is she's in her mid 40s, middle class and its summer. the death needs to take place at her home.
Carbon monoxide seems the best but not sure what appliance could be used and "faulty" in the summer.....Any ideas?!