"" What if it leads to an unknown terrorist cell?" Mark
M. Sandefur, whose son was killed in the attack,
wrote in a letter to Apple chief executive Tim Cook
that accompanied the filing . The letter alluded to the
lingering belief some have that there was a third
shooter in the attack. " What if others are attacked ,
and you and I did nothing to prevent it ?"
..."
https://www.washingtonpost.com/news/post-nation/wp/2016/03/03/tech-firms-relatives-of-san-bernardino-victims-weigh-in-on-the-apple-fbi-court-fight/