plus, shields and gerson and author ann patchett gets personal in a new collection of essays. >> woodruff: in march 2007, an american and former f.b.i. employee stepped into a taxi in iran and then vanished. he's rarely been heard from since, but as jeffrey brown reports, there are new details emerging about what u.s. officials knew about his circumstances, and when. >> brown: it's been nearly seven years since retired f.b.i. agent robert levinson disappeared in the iranian resort region of kish island. in 2010, a hostage video showed levinson was indeed alive. >> i have been treated well and i need the help of the united states government to answer the requests of the group that has held me for three and a half years. and please help me get home. >> brown: that spurred his son and wife to post their own plea for help in his return. >> please tell us your demands so we can work together to bring my father home safely. >> brown: but the trail went cold. for years, the u.s. government maintained levinson was a private citizen on business trip at the time. but yesterday, the associated press