Law enforcement block road near Nancy Guthrie's home during investigation into her disappearance

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TUCSON, Ariz. (AP) — Law enforcement investigating the disappearance of “Today” show host Savannah Guthrie 's mother sealed off a road near Nancy Guthrie's home in Arizona late Friday night.

A parade of sheriff’s and FBI vehicles, including forensics vehicles, passed through the roadblock that was set up about 2 miles (3.2 kilometers) from the house.

The Pima County Sheriff’s Department said the activity was part of the Guthrie investigation but declined to detail specifics.

Guthrie, 84, was reported missing on Feb. 1. Authorities say her blood was found on the front porch of her Tucson-area home. Purported ransom notes were sent to news outlets, but two deadlines for paying have passed.

Authorities have expressed concerns Guthrie’s health because she needs daily medication. 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.

Investigators have studied surveillance video, sorted through thousands of tips and submitted DNA and other evidence for laboratory analysis.

The FBI said it has collected more than 13,000 tips since Feb. 1, the day Guthrie was reported missing. The sheriff’s department, meanwhile, said it has taken at least 18,000 calls.

On Tuesday, authorities released footage showing an armed, masked person at Guthrie’s doorstep on the night she was abducted. The videos — less than a combined minute in length — gave investigators and the public their first glimpse of who was outside Guthrie’s home in the foothills outside Tucson.

Experts say the video could contain a mountain of clues. ___

Associated Press writer Audrey McAvoy in Honolulu contributed to this report.