Jeffries was a marine serving on Helghan during the invasion of Helghan. He was entering the battle at the Corinth River when he notices his old friend, Dante Garza engaging a group of Helghast. He is able to stop the Intruder to talk with Garza.
As the ship pulls away, it is knocked out of the air by an RPG. After another small engagement, Garza and Sev arrive at the crash site just in time to witness Jeffries' execution. As the soldier pleads for his life, a Helghast soldier shoots him in the head, killing him instantly. Garza and Sev then take revenge on the Helghast in retaliation for the young man's death.