Fullam was last seen leaving a friend's home in Smithtown, Long Island, New York at 10:45 p.m. on October 30, 1981. She was planning to go meet her brother and go with him to a nightclub in New York City. Fullam never arrived and has not been heard from again.

Fullam lived with her family in the 200 block of Mount Pleasant Road at the time of her disappearance, and her parents and teachers described her as a normal teenager who was close to her siblings and got average grades in her classes at Smithtown High School West, where she was a senior. However, she had both smoked and sold marijuana, and she had been arrested for selling LSD to an undercover police officer on three different occasions, twice at school and once at her home. She pleaded guilty to one count as part of a plea bargain and faced the possibility of a year in jail, but disappeared five days before sentencing. Fullam was reportedly frightened at the prospect of going to jail, but her lawyer believed she would be treated leniently, since she had no prior criminal record.

Besides her legal troubles, things were apparently going well for Fullam at the time of her disappearance. She had just been hired as a waitress at a local restaurant and was excited about it, and she had a good relationship with her boyfriend. The police assumed she had dropped out of sight to avoid facing the possible jail sentence, and they issued a warrant for her arrest. Her family and her boyfriend, however, never believed she ran away, and they think foul play was involved in her disappearance. Fullam left all her belongings behind when she disappeared and had less than $1 in cash on her that night, which is inconsistent with the runaway theory. Her case remains unsolved; there's been no sign of her since 1981.