Lieutenant Egan

Lieutenant Egan is the main villainess from "Eye Spy," episode 1.11 of NCIS.

She was played by Katy Boyer.

Lieutenant Egan served in the U.S. Navy along with her husband, Lieutenant Commander Thomas Egan. However, Egan had learned that Thomas was engaged in an affair with Lieutenant Commander Lauren Tyler, with the affair taking place during their work at SideScan. Furious over the affair, Egan confronted her husband at a nearby beach, where she took his diving knife and killed him. The villainess also took possession of a prototype for a sonar device that SideScan was working on, while also devising her evil plan to frame Tyler.

After Gibbs and DiNozzo learn that the killer was female and left-handed, the former pointed out that Lt. Egan is a left-handed golfer, and both deduced that she was her husband's killer, despite Caitlin Todd's disagreement of the claim. Gibbs and Caitlin visited Mrs. Egan at her home; where Gibbs falsely stated that Tyler killed Thomas because he threatened to expose a flaw in the sonar device, and that Tyler took the prototype to hide the truth. Sure enough, later that night, the evil Egan entered her car with the prototype and drove to a secluded area--where she buried the device and her murder weapon. Just as she was about to take the device and complete her plan to frame Tyler, she was caught by Gibbs, Caitlin, and DiNozzo, who followed her thanks to Abby's former flame, Ashton--a satellite tech for NASA--tracking the prototype's signal. Her villainous plan foiled, Lt. Egan was arrested (off-screen) for killing her husband.