The Skeena Region covers 327,275 km². Mostly wilderness area, covering almost the entire northwestern quarter of British Columbia. Field work is currently being restricted to projects within the Nadina Forest District, a small portion of the entire region, covering 2.6 million hectares (26000 km2.)
Disappearances: People have vanished without a trace since the 1800's, that I am aware of.
See also, Highway of Tears website.
A person just needs to get out there. Relying on witness reports for the MOST part, won't help you. Your work needs to be more field work than anything else. Once you do, and you have figured it out, you will understand what I mean.