Article continues below advertisementInvestigators assigned to the case of Savannah Guthrie's missing mom, Nancy Guthrie, are focusing on items the purported suspect allegedly purchased at Walmart. Pima County Sheriff Chris Nanos told CBS News on Monday, February 16, that authorities believe the clothing, ski mask and backpack worn by the person in the chilling surveillance photos released last week were bought from the popular superstore. Chris shared that investigators have spent days reviewing CCTV footage at local Tucson, Ariz.