Details of Disappearance Kathleen was last seen at her home in the Gulph Mills section of Upper Merion Township, Pennsylvania on December 3, 1999. She planned to spend the weekend with her boyfriend, Robert Linder, in Levittown, Pennsylvania; she'd spent most weekends with him for several months.
She almost canceled her plans because she had Christmas presents to wrap, but she ultimately decided to go and take the presents with her. She never arrived in Levittown and has never been heard from again.
Kathleen and her husband, Dr. Thomas Mohn, had been married for twenty years by the time she vanished. Though they still lived in the same house, they were estranged and both were seeing other people.
Kathleen had consulted an attorney about a possible divorce and learned she was entitled to thousands of dollars in monthly support payments and 65% of Thomas's dental practice. She worked at his dental office as an X-ray technician.
Thomas reported Kathleen missing after Linder called to ask why she hadn't arrived. He said his wife had left the house at 9:00 p.m. and he never saw her again.
Two weeks before Christmas, he brought wrapped Christmas presents for Kathleen's family to her father in Delaware, saying he was giving them to him because he didn't know when Kathleen would return.
A security video at the Bristol exit of the Pennsylvania Turnpike shows Kathleen's green 1993 Ford Explorer SUV with the Pennsylvania license plate number WR35703 exiting the turnpike at 9:54 a.m. on December 4.
The tape shows a blonde woman leaning against the passenger side window. The driver of the Explorer isn't visible, except for one arm. This was the last trace of Kathleen.
Kathleen's car was found on December 13th in the parking lot of a now-defunct Kentucky Fried Chicken restaurant at Route 13 and Levittown Parkway in Tullytown, Pennsylvania. A restaurant employee said the vehicle had been there since at least December 5.
Kathleen's eyeglasses, purse, cigarettes and prescription medication were inside her car, but her wallet was missing and so were the Christmas presents she'd planned to bring to Levittown. The vehicle was very clean, and Kathleen's car was normally dirty with cigarette ashes and other debris scattered everywhere.
The driver's seat was pushed back to accommodate someone much taller than Kathleen. There were several air fresheners inside the car, and Kathleen never used air freshener. A cadaver dog indicated the scent of human remains in the passenger compartment of the SUV.
Linder has been cleared of involvement in Kathleen's case, but investigators consider Thomas a strong suspect.
Stains similar to blood were found on a wall at the Mohn residence, and a dirty shovel and soiled clothing were in the outdoor shed. Thomas hasn't cooperated with the police in the investigation, but he hasn't faced any charges in connection with his missing wife and he maintains his innocence.
Foul play is suspected in Kathleen's case, which remains unsolved.
- Upper Moreland Police Department
Updated 4 times since October 12, 2004. Last updated August 3, 2010; picture added.