The search for the missing mother of Today show host Savannah Guthrie continued on Thursday as investigators revealed they had received more than 18,000 calls about the case. A search of desert terrain near her Arizona home came up mostly empty.

Almost a quarter of the tips came in during the 24 hours since the FBI on Tuesday released door camera video and still images of a masked and gloved suspect outside Nancy Guthrie’s home in the Catalina Foothills area north of Tucson early on 1 February, the Pima county sheriff’s office said.

Despite the surge of information, no new suspects have been identified in the hunt for the abducted 84-year-old. A man detained at a traffic stop on Tuesday in Rio Rico, about an hour south of the Guthrie residence, was released without charge after several hours of questioning.

On Wednesday, authorities conducted an “extensive search” of multiple roadways close to the Guthrie home. KVOA, the local NBC-affiliated TV station, reported the recovery of a pair of black gloves, which have been submitted for DNA testing, but said it is too soon to know if they are connected to Guthrie’s disappearance.

The Pima county sheriff’s department, which said it was sifting through 4,000 calls received since publication of the images, has not held a media briefing for a week, and said Wednesday in a post on X that none will be held unless there was “a significant development” to report.

KVOA said the lack of progress in the investigation was frustrating and causing anxiety for local residents. “We are very worried. The neighbors are all worried, and we do not know who this kidnapper is, what he’s done with Nancy Guthrie. We don’t know what’s going on, so we’re really concerned,” Marla Handler, a neighbor of the missing woman, told the outlet.

The station reported that Ring doorbell camera users in Catalina Foothills were asked by investigators for footage from 11 January from 9pm to midnight, and said there was “footage of interest” from the morning of 31 January relating to a suspicious vehicle. Authorities have not confirmed the information.

In a separate development, TMZ reported that it received a note early Wednesday from an anonymous person demanding one Bitcoin (about $67,000) from the Guthrie family “if they want the name of the individual involved”. The note has not been formally authenticated, and neither the FBI or Pima county sheriff has commented on it.

Separate purported ransom demands have been received by a number of Tucson-area television stations in recent days, with at least one deadline passing on Monday. Savannah Guthrie, who has presented NBC’s Today show since 2012, posted a video on social media the same day, asking for prayers and information.

“We believe our mom is still out there. We need your help. Law enforcement is working tirelessly, around the clock, trying to bring her home, trying to find her. She was taken and we don’t know where. And we need your help,” she said.

Detectives have searched the Guthrie home and surrounding area several times. Signs of forced entry and blood were found on the doorstep, Chris Nanos, the Pima county sheriff, has said previously, prompting him to declare it a crime scene.

Investigators were also at the Tucson home of Savannah Guthrie’s sister, Annie Guthrie, at the weekend as “part of a follow-up search in the normal course of the case”, NBC reported, citing an unnamed law enforcement official.

Nancy Guthrie has limited mobility and requires daily medication for her condition to keep her alive, her family has said.