In Independence Day, Vietnam vet & redneck crop duster pilot Russell Casse was supposedly abducted by the alien invaders in 1986. He ended up a crazy alien conspiracy nut, shunned by others, which lead to his drinking problem. In 1996, when the aliens publicly arrived en masse, he was arrested for public disturbance, but soon let go. The alien attack proved that he was likely telling the truth.
But why would the aliens, having abducted him in 1986, have let him go? They clearly have no compassion for humans, attempting to slaughter them wholesale. Did he escape, or is there a reason for returning him?