NRK (the Norwegian Broadcasting Corporation) have a web site about this case: https://www.nrk.no/dokumentar/gaten-i-isdalen-1.13182053 (English version: https://www.nrk.no/dokumentar/xl/the-isdalen-mystery-1.13249...).

There are a few other mysterious cases of unidentified people, the most famous of which is the Somerton Man (https://en.wikipedia.org/wiki/Tamam_Shud_case) (warning: contains mortuary photograph).

There's also Peter Bergmann (https://en.wikipedia.org/wiki/Peter_Bergmann_Case) (warning: contains mortuary photograph) and Lyle Stevik (https://en.wikipedia.org/wiki/Lyle_Stevik).

Two recent British cases have been solved, Emmanuel Caillet (https://www.theguardian.com/theguardian/2002/jan/05/weekend7...) and David Lytton (https://en.wikipedia.org/wiki/David_Lytton).