Washington: A locked iPhone used by one of the gunmen in last year's mass shooting in San Bernardino, California, likely holds evidence of the eventual attack, the Justice Department said in a court filing in its encryption dispute with Apple Inc, adding that the community and the public "need to know" what is on the device.

The government's filing is aimed at encouraging a federal magistrate judge to affirm her order from last month that directed Apple to help the FBI gain access to the phone used by Syed Farook, one of the two attackers in the December 2 shootings that killed 14 people.