As the hunt for missing Nancy Guthrie approaches its second week, investigators were seen searching a septic tank at her home in Tucson, Arizona, on Sunday.

Footage captured law enforcement using a pole to check inside a manhole behind Nancy’s $1million house, amid mounting fears that time is running out to find the 84-year-old mother of Today show anchor Savannah Guthrie alive and well.

Former SWAT team captain Josh Schirard told the Daily Mail: ‘A lot of people forget that having a septic tank means waste water doesn’t go into a city sewer, it goes into the tank.

‘So, somebody may have flushed something thinking that would get rid of it, but instead it would actually just be deposited in the septic tank. It is a possibility that [investigators] are now trying to make sure that there’s nothing in there that could indicate any kind of guilt.’

Nancy was reported missing by family last Sunday at noon after she had failed to attend church. Police found blood, now confirmed to be hers, spattered on her front porch, while her daily essentials – her phone, wallet, medications – all still inside.

She was last seen by her daughter Annie Guthrie and her son-in-law Tommaso Cioni, Annie’s husband. On Saturday night, Nancy had dinner at their nearby home and was driven back by family shortly before 10pm.

At 2.28am on Sunday, her pacemaker disconnected from her phone.

Ever since, there seems to have been very little in the way of substantial search developments. Cops even initially turned the crime scene back to family, before returning hours later to put police tape back up.

As the hunt for missing Nancy Guthrie approaches its second week, investigators were seen searching a septic tank at her home in Tucson, Arizona, on Sunday

Investigators are treating this as an abduction and say they believe Nancy is still alive.

Most revelatory has been a series of alleged ransom notes, sent to the Guthrie family via multiple media outlets. While the full details of the notes have not been published, it has been revealed that they have contained two deadlines and demanded payments in Bitcoin. The first deadline of 5pm local time on Thursday has now passed. A second deadline of 5pm on Monday is now furiously approaching.

NBC star Savannah, 54, has used her Instagram account (with its 1.6 million followers) to post a series of videos directly addressing her mother’s captors.

On Wednesday, she pleaded for proof of life.

On Saturday, she shared an update, simply saying: ‘We received your message and we understand. We beg you now to return our mother to us so that we can celebrate with her. We will pay… this is very valuable to us.’

Investigators are still working to determine the veracity of the ransom notes, but clearly they are being treated as real in the meantime.

Former SWAT team captain Schirard said: ‘It is not outside the realm of belief to think that the ransom notes could be fraudulent. Especially when you don’t have an established two-way communication, there’s been no proof of life.

‘I worked a lot of hostage rescues, and a ransom note or a hostage demand is very rarely, in my experience, [dragged out] this long.

‘Demands are usually within hours, you know, “I want this within four hours”. Maybe up to eight hours. But not days or a week. And it’s not usual to have these multi-stage demand timelines either.

‘It is very abnormal to see a multi-stage demand process that has such large gaps. Especially with no two-way communication. No proof of life.

‘There’s still a decent part of me that believes that the ransom notes are not legitimate.’

Fox News have reported that the ransom could be as much as $6 million, though investigators have not confirmed that figure.

Time is of the essence, and with 5pm on Monday approaching, Schirard said: ‘The clock is ticking and, even if it’s not a real ransom, even if Nancy [hasn’t been abducted and is] out there somewhere, you know, having unfortunately got lost, time is still running out to find her [alive].’

So what if Monday’s deadline is passed with no further updates?

‘At some point they will have to start pivoting the investigation away from leads that aren’t bearing fruit. You have to say, “Okay, look, we’ve devoted enough resources, allocated enough assets into this, spend enough time. It hasn’t given us anything. Let’s shift focus toward something that may give us a little bit more,’ Schirard said.

‘I would speculate that if Monday’s deadline passes with no more communication, with no proof of life, with no proof of consequence either, then obviously the investigation will shift to another direction and start working the next most plausible lead.’

Nancy Guthrie was last seen on Saturday night by family. In the early hours of Sunday morning, her pacemaker stopped connecting to her Apple Watch

On Saturday, authorities were spotted conducting a late-night search of Annie Guthrie’s home.

Police took photographs at Annie and husband Cioni’s home until around 10.30pm, NewsNation reported.

An agent was said to be seen carrying a silver briefcase into the home.

‘They were leaving with a Cellebrite [case],’ Schirard said. ‘Cellebrite is a company that specializes in recovering digital forensic evidence. So we use Cellebrite pretty extensively to recover digital evidence from phones, devices, tablets, computers.

‘When you delete a picture off your phone, it’s not actually gone. When you delete a picture or a Word document from a hard drive, it’s not actually gone. Cellebrite can go in and pull all this. So text messages, photos, location data, phone calls, all this stuff can be retrieved.

‘It’s likely that [police] were possibly looking at some of the family’s devices. And of course it would appear that the family have been incredibly cooperative.’

At a press conference on Thursday, Pima County Sheriff Chris Nanos said there were no prime suspects.

‘We think from movies and TV shows that there’s one piece of evidence, a smoking gun, that leads you to a particular person,’ Schirard said. ‘But more often than not, it’s an amalgamation of evidence that points us in a direction. It is like searching for a needle in a stack of needles.’