The 3 biggest challenges as the Nancy Guthrie case stretches into week 3

By Elizabeth Hartfield, CNN (CNN) — It’s been 16 days since Nancy Guthrie was reported missing, and investigators working the case that has captivated the nation’s attention are encountering a unique mix of challenges. The secluded area in Arizona where Guthrie lives and appears to have been kidnapped in the early morning hours of February