What you described above was one of the most interesting chapters in both U.S. and Argentine modern history.
Patt Derian, who learned the ropes as a civil rights activist in Mississippi, was herself arguably the most fascinating official in the beleaguered Carter administration - which I still think of as a "second Camelot" in many ways for the integrity, transparency, and departure from the good-ole-boy/warmonger form of governance we've had almost continuously since Vietnam.
Carter lacked Kennedy's charisma; but like Kennedy, Carter sought reform and real changes - above all to our foreign policy and all its bad faith. And like Kennedy, he found that resistance to even modest changes can be overwhelming. Carter was eventually stopped by gas lines orchestrated by oil industry "maintenance shutdowns" (the day after Poppy Bush announced he was running in 1980).
We all know how they stopped Kennedy. 
As a final note, here's an interview Patt Derian granted in 2009 to Argentine activist Juan Mandelbaum (Jews bore a disproportionately heavy brunt of Dirty War fatalities, as you may know). Not for the faint of heart.
http://www.ourdisappeared.com/videos/patriciaderian
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