Retired agent Dana Ridenour served 20 years in the FBI.  In this episode of FBI Retired Case File Review, she is interviewed about working drug investigations on the island of St. Croix, Resident Agency out of the FBI's San Juan Office in Puerto Rico and going deep undercover in California to infiltrate and build relationships with individuals associated with the animal rights extremist groups to gather intelligence about criminal activities and the location of activist fugitives. Dana explains how, in order to be successful, undercover agents accept that their job is to "build relationships to betray relationships."