Last Friday, Diana Paz was walking in the median near Mannheim Road in Westchester when she was hit by a truck.
State troopers say Paz had been arrested a few hours earlier for driving the wrong way on the expressway and charged with drunk driving.
Paz's family wants to know why the Illinois State Police released Paz and dropped her off at a gas station when she may have still been drunk.
"We really don't know what happened or how it happened," said Maria Paz, the victim's sister. "It seems it was just not fair for her to end like this."
Illinois State Police report that under law Paz was able to release herself and that she was alert and coherent at the time of her release.