Shannon was last seen in Baltimore, Maryland on March 3, 1984. She resided in the 2300 block of Foster Avenue at the time. She apparently climbed out of her bedroom through a window in the middle of the night and went to attend a party. She has never been heard from again. She left a note behind.

Shannon's parents were separated at the time of her disappearance and she lived with her mother. Her father lived in Mississippi. Shannon was reportedly looking forward to visiting him there that summer, and she seemed happy. Originally it was believed that Shannon had left of her own accord and gone to stay with her father or another relative, but now she is considered to be missing under suspicious circumstances.

Shannon's mother received a letter from her on March 8, five days after she disappeared; it was postmarked Orlando, Florida. No one has heard from Shannon since then. Prior to her disappearance she made several long-distance telephone calls to Florida, Colorado and Mississippi. It is unknown if the calls were related to her disappearance, which remains unsolved. Due to the lack of information in Shannon's case, it is classified as a non-family abduction.