India, Feb. 16 -- Investigators searching for missing 84-year-old Nancy Guthrie may find crucial clues in cellphone data, according to a retired FBI agent who says advanced tracking tools could play a pivotal role in the case.

Guthrie, the mother of Savannah Guthrie, was reported missing on February 1. Authorities have been investigating her disappearance for over two weeks, pursuing digital evidence, surveillance footage and public tips.

Jason Pack, a retired FBI supervisory special agent and former chief of staff for FBI Public Affairs, told Fox News Digital that the bureau's Cellular Analysis Survey Team (CAST) is among the most valuable tools in missing-person investigations, reported The Mirror US.

"They have data, mountains of it...