Expert claims Nancy Guthrie investigation 'becomes harder' over time

Nancy Guthrie has been unaccounted for 45 days, and with the most recent development offering little assistance to investigators, an expert commented to CBS News that the prolonged timeline means it "becomes much harder to keep the investigation going."

Officials shared with CBS News that new footage was obtained in recent weeks from security cameras placed at Guthrie's residence in Tucson, from where she is presumed to have been taken in the dead of night on February 1.

The footage, captured by a camera mounted on a fence focusing on the rear of the house, and another showing the driveway and garage entrance, featured family, landscapers, and pool maintenance personnel from several weeks prior to her kidnapping.

No suspicious activity was noted, and the suspect was not seen on the doorbell camera footage.

In the seventh week since the 84-year-old mother of "Today" co-host Savannah Guthrie vanished, the doorbell camera footage shared by the FBI on February 10 remains the only known images of the suspect.

Lance Leising, a retired FBI supervisory special agent, told CBS News this indicates "a shortage of substantial leads. That's the immediate impression it gives me."

"Continuing the investigation, keeping it relevant, and pursuing new leads becomes much tougher," he remarked.

DNA from the location is still under analysis, with detectives employing forensic genetic genealogy hoping it would crack the case.

This method previously aided in catching notable offenders, like Bryan Kohberger, who was responsible for killing four University of Idaho students in 2022.

Leising cautioned, though, that this method "requires time."

"It's possible to have multiple individuals from the same DNA family who might be suspects. Each must be examined separately," he explained.

Authorities are still receiving tips, with more than 1,500 potential leads reported to the FBI after the Guthrie family put up a $1 million reward.

However, it's been close to three weeks since the family made any public appeal, and over a month since the authorities briefed the media on the investigation.