Wilmer moved from Long Island, New York to California in late 1992, and moved into a rented house with roommates. She had attended St. Mary's High School in Manhasset, New York and got a full scholarship to St. John's University in New York City, but she dropped out after one semester. After her move to California she planned to enroll in the College of the Redwoods in Eureka, California, but all the classes were full. She at first found work as a waitress, but lost her job and accepted public assistance for a time.

Wilmer was last seen in northern California on September 13, 1993. There are two conflicting accounts of her whereabouts on the day of her disappearance. One summary states that Wilmer was last seen leaving her residence in Willow Creek, California to go to a travel agency to retrieve an airplane ticket for a scheduled trip back to New York. She never arrived at the agency and has not been seen again. The second account states that Wilmer was last seen hitchhiking from the Hawkins Bar area of California to Willow Creek for a possible job opportunity at a farm on September 13. Wilmer has never been heard from again and her case remains unsolved. Foul play is suspected in her disappearance.

Wilmer's mother assisted in creating federal legislation aimed at requiring states to report information concerning unidentified bodies into the National Crime Information Center (NCIC) database. This procedure provides easier cross-referencing of missing persons and unidentified victims in the United States. The legislation, titled Jennifer's Law, was signed into effect in 2000.