Lande was last seen during the early morning hours of December 12, 1971 in the Overbrook Park neighborhood of Philadelphia, Pennsylvania. Her parents were on a cruise vacation at the time. Lande spent the evening of December 11 at home watching television with two female friends. At approximately midnight, her boyfriend, Robert Thomas "Bobby" Nauss Jr., called her and asked her to come visit him for the weekend. Lande's friends tried to dissaude her from going, as it was late and they disliked Nauss. She decided to see him anyway, however. Her friends left a short time later. At 1:50 a.m., Lande's across the street neighbor heard a noise outside and looked out his bedroom window. He saw Lande walk out her front door and get into a gold Oldsmobile Toronado that was waiting for her. She has never been heard from again.
One of Nauss's friends later stated he saw Lande's corpse hanging from the rafters of a parking garage behind the friend's apartment building early on December 13. The friend helped Nauss dispose of the body in the Pine Barrens area of New Jersey, near Williamstown, New Jersey and about sixteen miles outside of Philadelphia. In 1977, Nauss's friend attempted to lead police to the body. He said he it had been buried in a wooded area which was later occupied by a subdivision. Authorities dug at several places, but were unable to recover Lande's remains. At trial, Nauss admitted Lande was dead, but stated she had taken her own life and he had not harmed her. However, several psychiatrists who testified at the trial did not believe Lande was suicidal at the time of her disappearance, and Nauss's friend testified that he had confessed to killing her.
Nauss was convicted of Lande's murder in 1977 and sentenced to life in prison. He escaped from prison in 1983, and was not located until 1990. While at large, he lived in Michigan under an alias name, married and had two children. Since his apprehension in 1990 he has remained incarcerated.
At the time of her disappearance, Lande was a student at Philadelphia Community College. Her remains have never been located, but foul play is suspected in her case due to the circumstances involved.