Part of the reason it is such a big news story is the fact it is two people committing the acts, that is quite rare, there have only been three instances in Canada’s history of known partner killers.
Just so you know, these two are a world wide news story, coverage is not restricted to Canada.
And no it isn’t a first, there was Homolka/Bernardo, Pickton, Millard, which all come to mind as major media news stories off the top of my head.
And this one is a case of national security since the suspects are at large, so why wouldn’t it be all over the news?