As social media began to comment on the phrase, the headline changed to "Dawsonville mother shoots disabled son, self." Later, they also re-wrote the lede. Here's my blog, with screenshots, on the story. Here's a link to the news item as it stands now.
My motto: write victim-centered stories. The phrase mercy killing, although indeed the murderer may have felt he or she was doing a mercy, is not something that should be blithely tossed about by journalists. Moreover, stories that fixate on the killer and his or her issues, rather than the life taken by the killer, is always the wrong way to go.
Here's another killer-centered story from a mother who murdered her child. This one took place in an Arizona hospital. Whereas the Hicks murder took place in a big house, so at least we can say there wasn't abject poverty, this story is tougher. Still, the coverage immediately leaps into looking to explain motives, using the child's disability to explain.
There is a time and a place for talking about services, about stress on parents, about the need for more community engagement when it comes to caregiving. That time isn't right after a murder. No journalist should imply that killing a person with disabilities is a mercy or justified.