An important but understated clue (spoiler)
Early in the film, Michael extols the benefit of exercise saying something (and I'm paraphrasing) like, "A healthy body leads to a healthy mind and spirit."
At Michael's deportation proceeding, the old woman recalls that Mishka, the war criminal, said this to her when he forced he to do push-ups with a large knife below her chest.
I picked this up when I first saw "Music Box" around 1990 on VHS and knew what the ending would be.