Marc was last seen in Des Moines, Iowa on March 29, 1986. He lived with his mother and two sibings on southwest Emma Avenue. On the day of his disappearance, he told his mother he was going to walk to a friend's home down the street and possibly see a movie. He asked his mother to save some pizza for him to eat when he got home. He never arrived at his friend's home. Marc's mother didn't realize he was missing until the next morning. After she called his grandmother and his friends and none of them had seen him, she called the police, but they refused to open an investigation until 48 hours had passed. Marc has never been heard from again.

According to his mother, Marc moved frequently back and forth between her Iowa home and his father's home in Minnesota in 1986. His case remains unsolved.