(NEXSTAR) – The investigation into the alleged kidnapping of Nancy Guthrie, the mother of “Today” show host Savannah Guthrie, has yet to turn up any suspects or persons of interest, Pima County Sheriff Chris Nanos told reporters at a press conference Thursday.

“We have nobody of interest, or any suspects you would consider a prime suspect,” Nanos said.

The press conference took place five days after Nancy Guthrie was reported missing by her family. Guthrie, 84, was last seen Saturday night after she was dropped off at her home in Tucson, Arizona, by a family member. She was reported missing the following day when she didn’t attend church.

Despite having no suspects, Nanos said officials are “not just sitting on our haunches waiting.”

“We have a number of leads coming in,” he said, explaining that the Pima Regional Critical Incident Team (PCRIT), which encompasses officials from multiple law enforcement agencies, was now assisting with the tips. “Every single lead is looked at. Every one of them.”

Sheriff Nanos also confirmed that an analysis of blood found on the porch of the home “came back to Nancy.”Until she’s found, he said, authorities will assume Nancy Guthrie is still alive, even though he remains “fearful” of the worst-case scenario.

“We just want her home, and to find a way to get to the bottom of all of this, just like you do,” Nanos said.

The day after Nancy Guthrie was declared missing, Savannah Guthrie asked her followers to “please pray” for her mother, calling her “a woman of deep conviction, a good and faithful servant.”

“Bring her home,” she concluded the message.

Reports soon emerged of a possible ransom note from the person or persons responsible for Nancy Guthrie’s disappearance, after which Savannah Guthrie and her siblings shared a video message on Instagram imploring those responsible to reach out directly with proof of life.

“We too have heard the reports about a ransom letter in the media,” Savannah Guthrie said, holding back tears. “As a family, we are doing everything we can. We are ready to talk. However, we live in a world where voices and images are easily manipulated. 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. Please, reach out to us.”

Echoing what the Pima County Sheriff’s Office had previously stated, Savannah Guthrie said her mother is without her daily medication, which she needs “to survive,” and to mitigate “constant pain.”She also addressed her mother directly.

“Mommy, if you are hearing this: You are a strong woman. You are God’s precious daughter, Nancy. We believe and know that even in this valley, he is with you. Everyone is looking for you, Mommy, everywhere. We will not rest. Your children will not rest until we are together again.”

“We rejoice in advance for the day that we hold you in our arms again,” she added. “We love you, mom.”At Thursday’s press conference, an agent with the FBI’s Phoenix field office announced a $50,000 reward for information leading to the recovery of Guthrie or the arrest and conviction of those responsible for her disappearance.

There’s also still time to “do the right thing,” Heith Janke, the Special Agent In Charge of the FBI’s Phoenix Office said, urging the kidnappers to return Nancy Guthrie before the situation worsens for everyone involved.

“Please return Nancy home,” Janke said.