Timothy, along with his sister Julie and mother Leslie, went missing from Katonah, New York on February 5, 1977. Leslie picked up the siblings from their father's home on Grandview Avenue and drove away in a white Ford Maverick with a green roof and a New York license plate number 636-WNA, but they were never seen or heard from again.

At the time of their disappearance, Leslie was separated from their father, Timothy Sr., but they had a cordial relationship. Timothy Sr. was not alarmed when Leslie didn't return home as he assumed she and the children had spent the night in White Plains. He reported them missing the next day.

Timothy Sr. has been ruled out as a suspect in their disappearance and was fully cooperative with the investigation. He also hired a private investigator and spent a considerable amount of time and money searching for his family. He has since moved out of New York.

There were no indications that Leslie had planned to leave and she didn't take any personal belongings or clothes with her. She also didn't withdraw a large amount of money from her bank account before her disappearance. Her mother passed away in 1994, and her obituary listed Leslie as a survivor.

The mystery surrounding the Guthrie family's disappearance remains unsolved, and their car has not been found. The circumstances of their case are unclear.