Melissa Ann Klahn was 16 and living in Tucson, Arizona, when she was last seen by her roommate on August 18, 2001. That sighting is the last confirmed contact; friends and family reportedly never heard from her again and phone calls went unanswered. She’s described as blonde, blue-eyed, about 5 feet 7 inches and 120 pounds.

The day she vanished has been described as ordinary, with no apparent arguments or signs of distress. The Tucson Police Department opened an investigation and her case is classified as Endangered Missing. There are very few public details and the central unanswered question is whether she left voluntarily or was taken.

If anyone knew Melissa, what information about her last days in Tucson could help investigators?