León Gieco is one of the main pop artists in Argentina, and surely for this reason he got problems with the military, some years ago (fortunately, we are now celebrating the 4th consecutive civilian transfer of government, for once in a century or so). Anything that doesn't move, just PAINT it. Anything that thinks, put it in jail or make it disappear. Those were the orders in those times.
I think you're right, Victor Jara may well be the Ghost mentioned by Gieco in his song. The most famous (if not musically the best) of his songs is EN EL PAIS DE LA LIBERTAD, which verses say:
BUSQUENME, ME ENCONTRARAN.. EN EL PAIS DE LA LIBERTAD! (look for me, you'll find me ... in FREEDOM LAND )
Gieco's melodies and rythms are highly influenced by USA folk and south latin America, I find some of them a delicious combination which stand for themselves in history of a whole-american folk if this should exist. Looking for a further opportunity to serve all Mudcatters to dig a little in Argentine and general southern music.
Un abrazo - Andrés