Null was last seen in Fort Lauderdale, Florida on the night of October 7, 1978. She and her nineteen-year-old boyfriend, Harry Wade Atchison III, who went by his middle name, attended a concert in Hollywood, Florida. After the concert, they were at Atchison's trailer in the 13300 block of southwest Fifth Court when they got into a violent argument. Atchison left angrily and got in his car, an orange 1969 Dodge Comet with Florida license plates, and started to drive away. Null chased after him, stopped him and got in the car. Neither of them were wearing shoes, and Atchison left his wallet behind. Neither of them returned or have ever been heard from again, and their vehicle was never located.

Atchison is described as a Caucasian male, 6'0 and 160 pounds with blond hair and green eyes. His date of birth is May 4, 1959. Photographs of him are unavailable. Because his parents were on a two-week vacation at the time he disappeared, they didn't immediately realize he and Null had vanished. After their return, Atchison's mother reported him missing. She later said the police believed he had simply run away. All of the records from the original missing persons report are now lost. Although Atchison was an occasional marijuana user and had dropped out of Miramar High School, he had a steady job as a carpenter and kept in touch with his parents.

Null was a freshman at Plantation High School at the time of her disappearance. Authorities believe both she and Atchison are dead; they theorize the couple accidentally drove into one of the canals in the neighborhood. Their cases remain unsolved.