Cache. Foriegn movie brainfuck

Alright, so this movie is supposed to have two solutions.  One is easy and says the movie is about France and Algeria but there is another where you find out who the killer is.  Anyone see this or can give me help or hints or even the whole solution to this movie?

Spoilers: it was the nigger

Spoilers: it was the nigger

I'm not so sure;  It is said there are two views on the movie, one that the general audience will get that is false and another that very few will figure out which is correct.  The black guy didn't do it. 

I have a theory that it was the Man himself, the main charecter video taping and sending all these tapes/pictures.  Anyone have a move in depth thought with supporting evidence that it was someone  other than the black man?