Nancy Guthrie was taken from her home early Sunday, authorities said.

Investigators swarmed Nancy Guthrie's home on Wednesday. They brought in K-9s and put up crime scene tape around the property. It's unclear why they have returned to the home.

“Our hearts go out to them,” Pima County Sheriff Chris Nanos said of Savannah Guthrie and her family. “This is their mom.”

The disappearance of "Today" show co-host Savannah Guthrie's mother, Nancy Guthrie, is being investigated as a crime.

The 'Today' co-anchor pleaded with her mother's potential abductor to "bring her home" in a new Instagram video

Savannah Guthrie and her siblings, Annie and Camron, released a tearful Instagram video pleading for the safe return of their 84-year-old mother, Nancy Guthrie. They also directly addressed her possible abductor and reports about ransom demands with readiness to communicate while demanding undeniable proof of life due to her urgent medical needs.

We need to know, without a doubt, that she is alive and that you have her. We want to hear from you, and we are ready to listen.”

Investigators searching for Nancy Guthrie have encountered several key challenges in the days since the 84-year-old mother of “Today” anchor Savannah Guthrie went missing, suspected of being taken from her home.