It was confirmed in November that The Mummy star Arnold Vosloo will play elite sniper Jacob Ripkin Broadsky in multiple episodes.
Nathan told TV Guide: "Booth is forced to confront the life that he led [as a sniper in the Army] when he sees a guy who's perverted the profession. The need Booth has to bring this guy to justice is going to hang over us for the rest of the year."
He added that the sniper's reign of terror will bring Booth and Brennan (Emily Deschanel) closer together.
"Whatever his relationship with [new girlfriend] Hannah, Brennan is always the closest person in his life," he suggested. "The sniper will affect Booth and Brennan in a very profound way."
Bones will return to Fox in 2011 in a new Thursday 9/8c slot.