Brad Mullin is a young Navy seaman stationed at Dam Neck in Virginia Beach, and (an unknowing) KGB informant. He grew up in a town near Casper, Wyoming, and joined the Navy because he "wanted to see the world." He is described by Philip as a "computer nerd, camera buff, classical music lover."
Elizabeth, pretending to be a victim of Larrick's abuse, manipulates Mullin's sensitive nature, and he ultimately copies Andrew Larrick's classified Navy files. Moments after giving them to Elizabeth, he realizes he will never see her again.