Someone was attacking women in Fairfax County and Alexandria, grabbing them from behind and sometimes punching and molesting them before running away. After logging 11 cases in six months, police finally identified a suspect.

David Lee Foltz Jr., who had served 17 years in prison for rape, lived near the crime scenes. To figure out if Foltz was the assailant, police pulled out their secret weapon: They put a Global Positioning System device on Foltz's van, which allowed them to track his movements.