New Delhi, Feb. 9 -- Police investigating the disappearance of Savannah Guthrie's 84-year-old mother, Nancy Guthrie, searched a septic tank behind her Tucson home on Sunday (February 8), as drone footage showed detectives opening a manhole cover in the backyard, according to reports.

Three detectives were seen sticking a long pole down the manhole, although authorities have not revealed what they were searching for.

On Sunday, two marked sheriff's cars and another vehicle arrived at Nancy Guthrie's house around midday. Investigators spent more than 20 minutes at the back of the home before leaving without comment.

Nancy Guthrie was last seen over a week ago after being dropped off at her home by her daughter, Annie Guthrie, and son-in-...