Melanie's father, the then-Kentucky state senator Bobby Flynn, called her at 4:00 p.m. on January 25, 1977 and asked her to bring some materials home from the Kentucky High School Athletic Association in Lexington, Kentucky, where she worked as a secretary. She promised she would bring the items home after going to a 5:30 p.m. doctor's appointment.
Melanie left work at 5:00 p.m., driving her red 1975 Ford Elite. She turned right off Cooper Drive onto south Limestone Street. Melanie never arrived at her appointment and never came home. She has never been heard from again. Bobby reported her missing three days later. Melanie is believed to have had only about $12 in cash on her person when she disappeared. She was supposed to get paid three days after her disappearance but never picked up the check. Her clothing and other personal belongings were left behind in her bedroom.
On February 8, a police officer found Melanie's car in an apartment building parking lot on Hollow Creek Road in Lexington. The surrounding area was known as a drug spot. Flynn's red leather coat was inside the car, and so was a suitcase left over from a trip to Louisville, Kentucky she'd taken the week before her disappearance. Her purse and the car keys were gone, however.
Bobby initially believed his daughter developed amnesia and wandered off. She fell off a running horse in 1972 and suffered a serious head injury that had her hospitalized for months, and she permanently lost her senses of smell and taste. In the months after her disappearance, police investigated leads that Melanie had gone to Florida. Several witnesses at the Texas Hotel in Daytona Beach identified her from photographs. They said the woman they spoke to had mannerisms similar to Melanie's, mentioned getting medical treatment for an allergy Melanie had, and talked about people whom Melanie knew. The woman in Daytona Beach was never located, however, and it was never confirmed that she was Melanie.
Melanie was working with the police at the time of her disappearance; she agreed to introduce a detective, Bill Canan, to members of the drug culture to avoid her own arrest for possession of marijuana. She took Canan to parties and introduced him as her boyfriend, but he denies that they never had a personal relationship. Canan does not believe the undercover work is related to Melanie's disappearance. Her family believes he is not being truthful about the nature of their relationship; they say he and Melanie were dating and Canan was a friend of the family. He was the officer to whom Bobby reported his daughter's disappearance.
During August 1977, Melanie's purse was found floating in the Kentucky River near Camp Nelson, twenty miles south of Lexington. The purse contained lipstick, a perfume atomizer, and two bottles of medicine, one of which was Melanie's antihistamines.
Bobby and Melanie's mother, Ella Ritchey Flynn, believe Canan was involved in their daughter's disappearance. He was never charged in connection with it, but he was arrested on federal drug charges in 1993. Bobby and Ella theorize that there was a police cover-up after Melanie's disappearance and evidence was suppressed. They have stated publicly their theory that Canan and possibly other police officers abducted and murdered Melanie. Melanie aspired to be a horse jockey or a singer at the time of her disappearance; she used the stage name Melanie O'Hara. She likes traveling and briefly lived in Cincinnati, Ohio. She was divorced when she vanished. Melanie's loved ones describe her as high-strung and energetic; they say she would never have left without contacting them eventually. Her case remains unsolved and foul play is suspected.