What could be learned from that phone that could not be collected from all the other electronics the couple owned and used?
Without accessing that phone the govt could find who the couple have called and texted, subpena social media sites for their exchanges, and collect who knows how much information under an NSL from Internet Service Providers.
I find it difficult to believe that something so nefarious or so important exists on that phone and that phone alone that can't be gathered elsewhere through other fashions.
This feels like the govt trying to flex its muscle using a high profile case in order to persuade public opinion regarding encryption and back doors.
Remember folks: a backdoor for one is a backdoor for all. And who cares about a back door when you have an intelligence agency monitoring all the comings and goings of the front door.