53-year-old bow hunter Robert Carter has been missing for more than a week and a rigorous investigation in Big Hole Battlefield National Park has turned up a few clues.So far, Carter's truck, and a series of footprints have been found. 

"It can take you all day to track what someone can walk in an hour, so we are behind him several hours from where he left his truck," Sheriff Franklin D. Kluesner said. " At the pace of man-tracking, if something happened late in the evening, we could still be numerous days out from where we could track right to him, but it does give us a direction of travel."

There’s a 40 square-mile patch of land that needs to be searched. On Friday, the number of searchers dwindled from 75 last Tuesday, September 22, to just 20 on Friday. Any volunteers are asked to stop by the incident command station first.

Sheriff Kluesner is hopeful for many volunteers over the weekend, but said the best tactic may be to call off the search on Monday, if Carter isn’t found.

"What could be done at that point is, if we suspend the search, we'll get people out of the area for several days," Kluesner said. "Because right now, the area is, scent-wise, full of a lot of the searcher's scent and things like that. Then we'll come back into the area with scent dogs and do aerial searches, looking for predators,  scavenger birds, that sort of thing."

Kluesner says scent dogs are being used now, but the area has so much human scent from the active search, that it may be preventing the dogs from finding Carter.