Melanson was last seen on the evening of October 27, 1989, at a party in Woburn, Massachusetts. She was last known to be in the company of two male acquaintances. Melanson did not take any personal belongings with her when she vanished. Police originally thought she had run away to Florida, but they are now investigating other theories with regards to her disappearance.

Melanie's family says she was happy with her life at the time of her disappearance and wouldn't have run away. She was looking forward to her upcoming birthday and the removal of her braces, and she was about transfer to Northeast Vocational High School and was excited about that.

In August 1992, an anonymous telephone caller told police to look for Melanson's body in an area pond. Investigators did search the pond, but found no evidence connected to her case. Melanson was in her freshman year at high school when she disappeared. Police believe she was the victim of foul play and is still in the general area. Her case remains unsolved.