Margaret was last seen in Burlington, New Jersey on June 24, 1974. She was planning to go to High and west Broad Streets in Mount Holly, New Jersey to have an interview with a man who called himself John Marshall. Margaret's younger sister accompanied her to the bus stop and saw her on. Witnesses reported seeing her near Mill and High Streets after she got off the bus in Mount Holly, but she has never been heard from again. She was carrying an eyeglass case with a Huckleberry Hound design at the time of her disappearance.

Margaret had advertised for a baby-sitting job, and Marshall responded to the ad on June 19. He told her he needed a babysitter for the following weekend, but he postponed meeting her several times. Finally he said he would meet her in a red Volkswagen. He gave Margaret a telephone number to reach him; the number was traced to a public phone booth at a supermarket in Lumberton, New Jersey. Margaret has never been heard from again. Several other parents in the area complained that someone had attempted to lure their daughters with fake job offers. A suspect's 1976 confession to involvement in her disappearance was widely publicized, but turned out to be a hoax.

Margaret took piano lessons in 1974 and she liked to ride horses. She graduted from St. Paul's Grammar School in Burlington two weeks before she vanished. Margaret's parents are now deceased, but her siblings are still alive and some still live in the Burlingto area. Her case remains unsolved.