New Delhi, Feb. 11 -- As investigators work to trace 84-year-old Nancy Guthrie, the internet has launched an investigation of its own. Nancy Guthrie, mother of US television host Savannah Guthrie, remains missing despite major developments in the case this week. Late Tuesday, authorities detained a person for questioning and executed a search warrant at a home in Rio Rico, Arizona - about 60 miles south of Tucson, near the US-Mexico border.

Yet even as law enforcement continues its work, online users have been attempting to decode grainy surveillance footage and piecing together theories - often based on incomplete or unverified information.

Earlier, the FBI released doorbell camera video from outside Nancy Guthrie's home taken the nigh...