Robyn Ann Pettinato was 14 when she vanished from Whitefish, Montana, on July 5, 1975. She was last seen walking barefoot on West Second Street toward a nearby softball field, wearing a tan halter top and cut-off denim shorts. Robyn was about 5 feet tall and weighed 100 pounds. Her purse and other personal belongings were left behind, and family members say she had no known problems at home or with friends, leading them and investigators to believe she did not run away.

In the days before she disappeared Robyn had been keeping a diary; her family gave it to investigators but it produced no clear leads. Police followed multiple avenues over the years, including interviewing her boyfriend (who reportedly passed a polygraph), looking for a young man mentioned in the diary, and checking on a reported sighting in Alaska. Foul play is suspected but nothing definitive has been found. Another teen from a nearby town disappeared less than a year later, but no concrete link has been established.