Article continues below advertisementSavannah Guthrie's 84-year-old mother, Nancy Guthrie, has been missing for more than 48 hours now, and authorities are worried she could be dead."It is a race against time, and I hope that window hasn't closed," Pima County Sheriff Chris Nanos told NBC's Liz Kreutz on the Today show on Tuesday, February 3. Authorities in Arizona have been investigating Nancy's disappearance since she was reported missing on Sunday, February 1, after failing to show up to church.