Andersen was last seen in St. Louis Park, Minnesota on November 15, 1981. An unknown individual picked her up at her parents' residence at 6:15 p.m. She has never been heard from again. Andersen was a regular patron of the Cardinal Bar in Minneapolis, Minnesota at the time of her disappearance. She left behind personal belongings including her medication, vehicle, clothing and toothbrush, and she has not used her checking account since her disappearance.

In 2002, police searched the vacant home of one of Andersen's former boyfriends, looking for evidence in connection with her disappearance. It is unknown what, if anything, was recovered. Andersen maintained a vegetarian diet in 1981. Her interests include motorcycles, yoga, pool and rock music. Her disappearance remains unsolved and is being investigated as a possible homicide.