Hillard was last seen in Houston, Texas on May 4, 1988. She called a friend at 8:30 p.m. and said she was going to bed. She has never been heard from again. Hillard's boyfriend went to her apartment the next morning and could not find her. He reported her missing after he learned she had not gone to work. The apartment was in good condition and nothing appeared to be missing from it. Some of the windows were left open, which Hillard was in a habit of doing.

Hillard's 1979 AMC Spirit sedan was discovered abandoned at an apartment complex in the 12800 block of Dunlap Street, a mile from her home, the day after her disappearance. The vehicle appeared to have been ransacked, Hillard's purse was missing, and blood was found on the back and the side of the car. There was no sign of her at the scene. Foul play is suspected in Hillard's case.