Authorities investigating the abduction of 84-year-old Nancy Guthrie have cleared her immediate family members as suspects, calling them fully cooperative.

The FBI is analyzing key DNA evidence found on a glove linked to a masked suspect seen outside her Tucson-area home the night she disappeared.

Surveillance footage shows an armed man tampering with a security camera before the Feb. 1 kidnapping, but no arrests have been made despite multiple searches and a detention.

A ransom note demanding $6 million in bitcoin was deemed credible, though officials have no proof the author has Guthrie, and the payment deadline passed without money exchanged, the Los Angeles Times has reported.

With Guthrie missing her heart medication and few concrete leads, concern for her safety is intensifying as the investigation enters its third week.