An unnamed man who impersonated Matthew Graham was the deputy director of the FBI.
After Nikita's escape it is discovered that "Graham" is a member of The Invisible Hand and has been tracking Nikita for their purposes. Graham ultimately kills Dale Gordon via an explosive device. This act is then pinned on Nikita.
In "Dead or Alive" it is revealed that he is Matthew Graham's double. After Nikita tried to blow his cover in front of the whole FBI, he decided to make it even worse for her. He returned home to see "his" wife, Sarah. He told her to stay in front of the window. A man shot her and then this double pointed to his arm, a place where to shoot. He survived the shooting and pinned it on Nikita. Nikita released a video in which Graham gets killed. While he was being interviewed Michael killed him by pressing a button which is linked to a gun taped on the camera.