The county sheriff’s department has said the suspect description “remains a key focus”, but added that “investigators are not ruling out any individuals or possibilities”.
Guthrie was last seen on 31 January, when a family member dropped her off at her home following a get-together at her daughter Annie’s house.
Members of her church noticed her absence the following day and notified her family.
In the two weeks since Guthrie’s disappearance, the FBI and Pima County Sheriff’s Office have conducted a massive search operation involving helicopters, sniffer dogs and hundreds of officers while taking in thousands of call-in tips.
Officials have warned that she may be in dire health without her medication. Pima County Sheriff Chris Nanos has said Guthrie was “not in good physical health” but had no reported cognitive issues.
On Friday, authorities executed a search warrant at a residence two miles from Guthrie’s home but made no arrests.
Local officials have also said investigators found DNA at Guthrie’s address that did not belong to her or anyone close to her.
The FBI has increased the reward for information about Guthrie’s disappearance from $50,000 (£36,700) to $100,000.