child is with parents....

Really?

i think someone else answered in another thread, but the mother seems to be off in hiding (possibly for aiding the kidnapping of a child ?) and the father is in jail possibly for shooting the state trooper, although I had thought that it was Lucas who shot the state trooper though.

The mother is not in jail. We see her in the gas station cutting off her hair with some packages of hair dye. The father is in jail for kidnapping a child (unsure whether Sam Shepard's character officially adopted Alton??), leading police, CIA, etc. on a wild goose chase, accessory to the shooting/death of a police officer, damage to police property by driving through their vehicles at the blockade and who knows how many other illegal things which occurred throughout this movie. But I think they basically just wanted to keep Roy (Michael Shannon) in jail because they saw him as the father of an alien and would keep him there maybe forever so as to never let him out of their sight... 