The FBI says a glove found near the home of US Today show host Savannah Guthrie's mother contains DNA and appears to match those worn by a masked person outside her front door the night she vanished.
The glove, found in a field near the side of the road in Tucson, Arizona, was sent off for DNA testing.
The preliminary findings from a private crime laboratory in Florida were received by the FBI on Saturday and were awaiting "quality control and official confirmation" on Sunday, the FBI said in a statement.
The results are submitted for comparison against known DNA profiles in a national database.
The process of running a specimen through CoDIS, short for the Combined DNA Index System, typically takes 24 hours.
Nancy Guthrie, 84, was last seen at her Arizona home on January 31 and was reported missing the following day.
Authorities say her blood was found on the front porch. Purported ransom notes were sent to news outlets, but two deadlines for paying it have passed.
Law enforcement and family members have described Ms Guthrie as being in frail health and in need of daily medication to survive. She also had a pacemaker.
Approximately 16 gloves were found in various spots near her house, most of which were searchers' gloves that had been discarded, the FBI said.
The discovery was revealed days after investigators had released surveillance videos of the masked person outside Ms Guthrie's front door.
A porch camera recorded video of a person with a backpack who was wearing a ski mask, long pants, jacket and gloves.
On Thursday the FBI called the person a suspect. It described him as a man about 175 centimetres tall with a medium build. The agency said he was carrying a 25-litre "Ozark Trail Hiker Pack" backpack.
Authorities have expressed concern about Ms Guthrie's health because she needs vital daily medicine.
She is said to have a pacemaker and has dealt with high blood pressure and heart issues, according to sheriff's dispatcher audio on broadcastify.com.
AP/Reuters
