Partridge left her classes at Ferris High School in Spokane, Washington at 12:30 p.m. on December 4, 1974, because she felt was suffering from cramps. She was unable to find a ride and decided to walk the two miles to her home in the 5400 block of south Custer Street. She was last seen walking south on Havana Street near 37th Avenue. Partridge never arrived home and has never been heard from again. Her parents reported her missing when she failed to report for work at the Lincoln Heights Theater.

Partidge's father had bought her tickets to a Beach Boys concert which took place after disappearance, and the police went to the concert to see if she would arrive there. They did not see her. It was later determined that Partridge's tickets were in fact used, but authorities were unable to find out who used them. Partridge was carrying a brown leather purse with a blue flower design and a braided shoulder strap at the time of her disappearance. The contents of the purse were located in the area where she was last seen on December 6, 1974, two days following her disappearance.

Authorities initially believed Partridge left of her own accord, but her family never believed this, and police have since revised their opinion; they now think she was taken against her will. She and her boyfriend were hoping to marry and were planning to select an engagement ring on the day of her disappearance. She worked for her high school newspaper and was on the school drill team. Partridge has five siblings, all younger than herself. She formerly lived in California and had expressed the desire to move back there.

Three suspects have been questioned in Partridge's case over the years, but no one has been charged. Her case remains unsolved.