Hernandez was last seen at approximately 8:30 a.m. on January 16, 2004, at Avance Headstart Child Care on Acme Castroville Roads in San Antonio, Texas. She carried a silver Sprint camera-style cellular phone and a Fiesta Texas handbag with red sides, and "Fiesta Texas Flags" written on it. Her billfold and identification were inside the bag.

Hernandez dropped her toddler daughter off at the child care center, then left to meet the father of her children and speak to him about their child support payments. She never arrived at her destination. Her car, a hunter green 1996 Ford Mustang with the Texas license plate number F19SBT, was later found abandoned at a strip mall in the 4800 block of West Commerce Street, near General McMullen Drive, on the west side of San Antonio. There was no sign of her at the scene, and no indications of foul play. The strip mall is only about a mile from Hernandez's apartment but her loved ones say she did not go there.

Hernandez was involved in a custody battle at the time of her disappearance; the father of her oldest son had been attempting to get full custody of him. She has three children, who are now staying with her parents. Hernandez's ex-boyfriend, the father of her two younger children, maintains his innocence but has refused to take a lie detector test in connection with her disappearance. The father of her older son is still trying to get custody of him.

Foul play is suspected in Hernandez's disappearance. She reportedly told her mother that if she did not return from her appointment, it was because she had been murdered. Her case remains unsolved.

Some agencies state Hernandez was last seen leaving her home, which is in the 2400 block of Rivas Street.