More than 4,000 calls came into an Arizona sheriff's department within 24 hours after the release of videos of a masked person on Nancy Guthrie’s porch.

Investigators in Arizona want residents near Nancy Guthrie’s home to share surveillance camera footage of suspicious cars or people in the month before the disappearance of “Today” show host Savannah Guthrie's mother.

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A man detained by police for questioning in the disappearance of Nancy Guthrie has been released while investigators hope that images of a masked person on her Arizona porch still will bring tips from the public to help solve her apparent abduction.

In a significant breakthrough in the Nancy Guthrie disappearance case, FBI investigators successfully recovered crucial doorbell camera footage that had initially been thought lost, revealing that digital evidence can sometimes persist even after devices are disconnected or damaged.

Investigators are still searching for Nancy Guthrie as the case reaches it's 11th day.

Chris Nanos has had a long career in law enforcement, but he admits he isn’t used to the amount of scrutiny that has come with leading the investigation into the disappearance of “Today” show host Savannah Guthrie’s mother.

Catch up on the latest news updates from Houston and around the world.

FBI agents are fanning out across an Arizona neighborhood not far from Nancy Guthrie’s home.

A man has been detained for questioning in connection to the disappearance of Nancy Guthrie, the mother of TODAY show co-host Savannah Guthrie, a person familiar with the matter told NBC News.

Investigators have found surveillance footage of an armed, masked person at Nancy Guthrie's doorstep on the night she disappeared.

Authorities are expected to release a surveillance photo showing a potential subject in the investigation into the disappearance of Nancy Guthrie, the mother of “TODAY” co-anchor Savannah Guthrie, according to two senior law enforcement officials.

Authorities are expected to release a surveillance photo showing a potential subject in the investigation into the disappearance of Nancy Guthrie, the mother of “TODAY” co-anchor Savannah Guthrie, according to two senior law enforcement officials.

Officials say a person has been detained for questioning in the disappearance of Nancy Guthrie.

The FBI says it is unaware of any continued communication between Savannah Guthrie’s family and suspected kidnappers.

The investigation into the apparent kidnapping of Nancy Guthrie, mother of "Today" show host Savannah Guthrie, continues.

Savannah Guthrie has told the potential kidnappers of her mother Nancy Guthrie that the family is prepared to pay for her safe return.

Moments after the news broke about the apparent abduction of “Today” show host Savannah Guthrie’s mother, the floodgates opened on social media.

It's frequently a challenge for a news organization to cover a story that involves itself, or one of its employees.

Experts say abductions for ransom are rare, despite dramatic portrayals on TV.

The sheriff investigating the apparent abduction of “Today” show host Savannah Guthrie’s mother says it’s frustrating that a camera at Nancy Guthrie’s home wasn’t able to capture images of anyone the day she went missing.

Savannah Guthrie made a heart-wrenching plea for “proof of life” of her 84-year-old mother.

The family of “Today” show host Savannah Guthrie is renewing their plea for their mother’s kidnapper to contact them.

NBC says that veteran Olympics broadcaster Mary Carillo will replace Savannah Guthrie as co-host of opening ceremonies for the Winter Games in Italy.

NBC “Today” show host Savannah Guthrie has sent a public message to her mother's kidnapper saying that her family is ready to talk but wants proof that she is alive.

“Today” show host Savannah Guthrie has described her mother over the years as selfless, loyal and as a woman of great of faith.

Investigators have found signs of forced entry at the Arizona home of “Today” show host Savannah Guthrie’s mother.

An Arizona sheriff says the disappearance of the 84-year-old mother of “Today” show host Savannah Guthrie over the weekend is being investigated as a crime based on what authorities saw at her home.