I believe that, through the NSA or other nefarious means, they have the full contents of every call, voice message, text, email, and web search/contact.
This is VERY illegal, as the NSA is only supposed to collect metadata, not content.
They cannot use this data without 'spilling the beans' and damning themselves.
They need Apple to knuckle under and give them cover as they use the illegally acquired data.
NSA does NOT have content, only meta-data.
Numbers called, location, how long.....
Yet, somewhere, the government has the data it seeks but will not admit to it, lest a myth it has foisted upon us all be burst. Since at least 2009, the government's domestic spies have captured the metadata -- the time, place, telephone numbers and duration of all telephone calls -- as well as the content of telephone calls made in America under a perverse interpretation of the FISA statute and the Patriot Act, which a federal appeals court has since invalidated.
The DoJ knows where this data on this killer's cellphone can be found, but if it subpoenas the NSA, and the NSA complies with that subpoena, and all this becomes public, that will put the lie to the government's incredible denials that it spies upon all of us all the time. Surely it was spying on the San Bernardino killers.