While in California, Karen has a routine blood test as part of an insurance policy application. The supervillain Mysterio, as part of a plan to psychologically destroy Daredevil for one last scheme, disguises himself as a doctor, performs the blood test, and tells her that she is HIV positive. Devastated, Karen returns to New York and tells Matt about the diagnosis. Using another disguise, Mysterio suggests to Karen that her infection is due to an infant that Matt is currently protecting as the child 'really' the Antichrist, but Matt forces her to acknowledge that she is just trying to avoid facing her own responsibility for her state. Later, during a fight between Daredevil and Bullseye, Karen is murdered by Bullseye when she moves to intercept a billy-club thrown at Daredevil's head and is impaled in the heart.