Savannah Guthrie says her family is offering a $1 million reward for her mother's return

“She may already be gone,” Savannah Guthrie said in an Instagram post. “She may already have gone home to the Lord that she loves and is dancing in heaven.”

Nancy Guthrie, 84, was last seen at her home just outside Tucson, Arizona, on Jan. 31 and was reported missing the next day. Authorities believe she was kidnapped, and the FBI released surveillance videos of a masked man who was outside Guthrie’s front door on the night she vanished.

Drops of her blood were found on the front porch, but authorities haven’t publicly revealed much evidence. Since the first days of her disappearance, authorities have expressed concern about Nancy Guthrie’s health because she needs vital daily medicine.

Savannah Guthrie said her family needs to know where her mother is no matter what happened.

“Someone out there knows something that can bring her home,” she said.

Several hundred people are working the Guthrie investigation, and more than 20,000 tips have been received, the Pima County Sheriff’s Office has said. The FBI and other agencies are assisting.

The porch camera footage released two weeks ago, which showed a man wearing a backpack and gloves outside Nancy Guthrie's house, gave investigators their first major break. But it also has fueled intense speculation.

The sheriff’s department said Monday that it’s aware of differences in the masked person’s clothing depicted in various images that were released, namely with and without a backpack.

“There is no date or time stamp associated with these images,” the department said. “Therefore, any suggestion that the photographs were taken on different days is purely speculative.”

Sheriff Chris Nanos said a week ago that members of Guthrie’s family, including siblings and spouses, are not suspects.

Savannah Guthrie said Tuesday that her family also will donate $500,000 to the National Center for Missing and Exploited Children.

“We are hoping that the attention that has been given to our mom and our family will extend to all the families like ours,” she said.