DNA recovered from a glove found near the home of Nancy Guthrie does not match anything in a national database, authorities have said.
It marks a significant setback for detectives investigating the case of the missing 84-year-old, who is the mother of NBC's Today show presenter Savannah Guthrie.
She was last seen on 31 January when her family dropped her off at her home near Tucson, Arizona, following dinner with them. The case has since gripped America and beyond.
Authorities announced they had obtained a DNA sample from a glove found near the property on Sunday.
The glove appeared to match the pair worn by a masked prowler seen in doorbell camera footage before Nancy was abducted, and forensic experts hoped to find a match on a national DNA database.
It was announced on Tuesday that no match had been found.
Pima County Sheriff Chris Nanos has said he believes the man in the doorbell video is the likely perpetrator of the abduction and the primary person authorities are looking for.
The Guthrie family, who have released several public appeals for help, have been ruled out as suspects and are holding out hope that Nancy is still alive.
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The disappearance is still being treated by police and the FBI as an apparent kidnapping for ransom.
Mr Nanos has said Nancy, who has a pacemaker, was extremely limited in her physical mobility and could not have left her home unassisted, leading investigators to believe she had been taken against her will early on.
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