Searching for a Heartbeat From the Sky - The Nancy Guthrie Case

[Luis Gonzalez]

Searching for a Heartbeat From the Sky - The Nancy Guthrie Case


Can a “Signal Sniffer” Really Locate Nancy Guthrie?

Helicopters overhead. Antennas scanning the ground. Reporters talking about searching for a “heartbeat from the sky.”

It sounds futuristic. A pacemaker acting like a beacon. A signal strong enough to guide rescuers from the air.

But here’s the hard question: are these devices really trackable from hundreds of feet above the ground?

Modern pacemakers transmit tiny bursts of data. They are built for medical monitoring, not long-range tracking. So what exactly is a “signal sniffer,” and how much of this is practical science versus public optics?

In high-profile searches, technology can look more powerful than it actually is.

Read the full breakdown at Boiling Frogs

[Smokin Joe]

If she is dead and buried, how many feet of earth could the signal escape, and what range would it have?

If she is being held in a bunker, same question.

Can the receiver/detectors be made light enough to put on drones which can fly closer to the ground? (and potentially cover much more area at less expense?)

[Luis Gonzalez]

If she is dead and buried, how many feet of earth could the signal escape, and what range would it have?

If she is being held in a bunker, same question.

Can the receiver/detectors be made light enough to put on drones which can fly closer to the ground? (and potentially cover much more area at less expense?)

It’s searching for a needle in a haystack.

[andy58-in-nh]

I believe that if this poor woman is ever to be found, it will be through the laborious process of police detective work, as opposed to mere technology. 

Not that technology would be entirely useless, as it may be employed to gather sales records and receipts from vendors who sold the (still unknown) suspect's backpack, jacket and gloves. But those records will need to be manually cross-checked and the names compared to databases and then researched and interviewed if it is deemed necessary to evaluate them as a suspect - which is a necessarily human process.

A flyover might detect a "ping" from her pacemaker, but with no identifiable search borders, the chances are diminishingly small.

The area surrounding the home will need to be picked over, quadrant-by-quadrant, foot by foot, with shoe leather on the ground. Leads will need to be followed up, which takes a great deal of time and effort by investigators who will be calling, texting, visiting and evaluating those they meet. Any and all information they obtain will then need to be assembled, categorized, and communicated to other investigative agencies.

All of this takes time, and shortcuts occasioned by lucky coincidences only happen on TV crime dramas.  Meanwhile: her friends and family wait and pray.

[rustynail]

Why did they tell that this was happening?

[Lando Lincoln]

Excellent piece as always, @Luis Gonzalez.

If she was dumped in the wild, desert coyotes are superb scavengers. Not good.

[BobfromWB]

Searching for a Heartbeat From the Sky - The Nancy Guthrie Case


Can a “Signal Sniffer” Really Locate Nancy Guthrie?

Helicopters overhead. Antennas scanning the ground. Reporters talking about searching for a “heartbeat from the sky.”

It sounds futuristic. A pacemaker acting like a beacon. A signal strong enough to guide rescuers from the air.

But here’s the hard question: are these devices really trackable from hundreds of feet above the ground?

Modern pacemakers transmit tiny bursts of data. They are built for medical monitoring, not long-range tracking. So what exactly is a “signal sniffer,” and how much of this is practical science versus public optics?

@Luis Gonzalez
A “signal sniffer” is a device invented and built by a guy that works for NSA.  He has looked for these types of signals before.

The tech involves high gain antennas and high powered amplifiers, such that a BT signal can be detected from 800 feet away.

He mentioned that pacemakers operate for 3 years. So there is time to find her body whereever it is in northern Mexico.

[Luis Gonzalez]

@Luis Gonzalez
A “signal sniffer” is a device invented and built by a guy that works for NSA.  He has looked for these types of signals before.

The tech involves high gain antennas and high powered amplifiers, such that a BT signal can be detected from 800 feet away.

He mentioned that pacemakers operate for 3 years. So there is time to find her body whereever it is in northern Mexico.

All that was addressed in the piece. It still the case that the pacemaker emits an incredibly weak signal and the snifter has to be very, very close to it to have a chance of detecting it.

The problem becomes nearly insurmountable when you throw in the fact that they have no clue (insofar as we know) about a specific area to search.

[BobfromWB]

All that was addressed in the piece. 

No it was only generally addressed - the sniffer used is a new invention. The guy that invented it is an expert in radio signal finding and as I mentioned he worked for NSA in that capacity. NSA is tasked with signal interception worldwide. His detector works up to 800 feet from the source; it is not bound by the "conventional" thinking here that BT signals can only be "heard" at 35 feet. If you know anything at all about how radio waves propagate, then you would know that interacting with a signal and detecting it are two different things.

[DB]

All that was addressed in the piece. It still the case that the pacemaker emits an incredibly weak signal and the snifter has to be very, very close to it to have a chance of detecting it.

The problem becomes nearly insurmountable when you throw in the fact that they have no clue (insofar as we know) about a specific area to search.

A high gain antenna is highly directional (the higher the gain, the more directional) and can receive/transmit digital radio signals from much greater distances. For example, a typical home WiFi system can be accessed from miles away with the right antenna as long as it has line of sight to that location.

[Luis Gonzalez]

No it was only generally addressed - the sniffer used is a new invention. The guy that invented it is an expert in radio signal finding and as I mentioned he worked for NSA in that capacity. NSA is tasked with signal interception worldwide. His detector works up to 800 feet from the source; it is not bound by the "conventional" thinking here that BT signals can only be "heard" at 35 feet. If you know anything at all about how radio waves propagate, then you would know that interacting with a signal and detecting it are two different things.

It’s the snifer 2.0.

If she is outdoors or lightly shielded, detection is plausible.
If she is inside a reinforced structure or vehicle, detection becomes far less reliable.

The closer investigators are, the better it works. The more shielding involved, the worse it performs.

That is the engineering reality.

[roamer_1]

This seems pretty unlikely.

BT in promiscuous mode, perhaps, but in any city the ground clutter (all the BT transmissions) are likely to obfuscate...

But IF they can mimic her cell phone, to which the device was paired - That's a 1 to 1 response... serial and highly identifiable.

Still an extraordinary find with such a weak signal. Even from a low flight.

What an interesting endeavor.

[rustynail]

They might have more success with cadaver dogs.

[DB]

This seems pretty unlikely.

BT in promiscuous mode, perhaps, but in any city the ground clutter (all the BT transmissions) are likely to obfuscate...

But IF they can mimic her cell phone, to which the device was paired - That's a 1 to 1 response... serial and highly identifiable.

Still an extraordinary find with such a weak signal. Even from a low flight.

What an interesting endeavor.

Apparently, it pings on a regular interval and will do so with a unique ID. So it only has to be received to find it. I don't know how long the battery will last or if it shuts down if the person is dead.

Then there's the question of if she is above ground or not, or inside a metal container. If she was moved out of the area, then the chances of detecting it are close to zero.

[Smokin Joe]

This seems pretty unlikely.

BT in promiscuous mode, perhaps, but in any city the ground clutter (all the BT transmissions) are likely to obfuscate...

But IF they can mimic her cell phone, to which the device was paired - That's a 1 to 1 response... serial and highly identifiable.

Still an extraordinary find with such a weak signal. Even from a low flight.

What an interesting endeavor.

I suppose it is possible that she is being held in a heavily populated area, but my guess at this point (and I hope I am wrong) is that signal would have to push through a couple of feet of dirt to get out.

I'd be buzzing the area with a drone looking for 'body sized' fresh excavations. Maybe visible, might show up on IR.

I'm not sure exactly what smell (chemical emission) cadaver dogs 'hit' on, but if a sniffer could be made to detect the same chemicals, maybe flying low would pick them up, too.

[roamer_1]

Apparently, it pings on a regular interval and will do so with a unique ID. So it only has to be received to find it. I don't know how long the battery will last or if it shuts down if the person is dead.

Then there's the question of if she is above ground or not, or inside a metal container. If she was moved out of the area, then the chances of detecting it are close to zero.

Even without all that, a BT sig is very localized. Weak. I don't know exactly how it carries, but in normal use it is way less than 300 ft. Even my Samsung watch, which is noted for it's BT... If I get the length of this house away from my phone, it's hollerin that it lost BT connection... 

Maybe not as weak as an RFID, but still pretty weak.

[roamer_1]

I suppose it is possible that she is being held in a heavily populated area, but my guess at this point (and I hope I am wrong) is that signal would have to push through a couple of feet of dirt to get out.

I'd be buzzing the area with a drone looking for 'body sized' fresh excavations. Maybe visible, might show up on IR.

I'm not sure exactly what smell (chemical emission) cadaver dogs 'hit' on, but if a sniffer could be made to detect the same chemicals, maybe flying low would pick them up, too.

I think low tech is best on that one... Cadaver dogs can smell a body cookin a mile away. Tech is hard pressed to beat that.

[Luis Gonzalez]

Apparently, it pings on a regular interval and will do so with a unique ID. So it only has to be received to find it. I don't know how long the battery will last or if it shuts down if the person is dead.

Then there's the question of if she is above ground or not, or inside a metal container. If she was moved out of the area, then the chances of detecting it are close to zero.

... and will continue to ping and work well beyond her death, until the long-life battery runs out.

[roamer_1]

... and will continue to ping and work well beyond her death, until the long-life battery runs out.

That's a big dang desert... Jussayin. 

[Luis Gonzalez]

I think low tech is best on that one... Cadaver dogs can smell a body cookin a mile away. Tech is hard pressed to beat that.

I used AI and mapped out the terrain in several radiuses: 1-5 miles, 5-10 miles and 10+ miles from her house.

In 10+ miles you are in an area that is serial killer body disposal paradise.

Holes and caverns dot the landscape.

[roamer_1]

I used AI and mapped out the terrain in several radiuses: 1-5 miles, 5-10 miles and 10+ miles from her house.

In 10+ miles you are in an area that is serial killer body disposal paradise.

Holes and caverns dot the landscape.

Like I said, that's a big dang desert. 

[Luis Gonzalez]

Looking at the area 10–20 miles out from Nancy, the terrain alone would explain why this search would be so difficult. It’s not flat desert. There are washes, canyon mouths, rocky slopes, and thick patches of cactus and brush. These features create natural corridors that animals, and unfortunately any remain, can move through or hide in.

Wildlife is a factor too. Coyotes, bobcats, javelina, and deer all roam freely. In the higher, rougher terrain, mountain lions are present. Seasonal water and dense vegetation can shift movement patterns and make some areas nearly impossible to comb thoroughly.

When you combine rugged geography with active wildlife, it becomes clear why this search is so unpredictable. Even small washes or hidden canyon pockets can obscure evidence. The landscape itself works against anyone trying to locate her.

[roamer_1]

Looking at the area 10–20 miles out from Nancy, the terrain alone would explain why this search would be so difficult. It’s not flat desert. There are washes, canyon mouths, rocky slopes, and thick patches of cactus and brush. These features create natural corridors that animals, and unfortunately any remain, can move through or hide in.

Wildlife is a factor too. Coyotes, bobcats, javelina, and deer all roam freely. In the higher, rougher terrain, mountain lions are present. Seasonal water and dense vegetation can shift movement patterns and make some areas nearly impossible to comb thoroughly.

When you combine rugged geography with active wildlife, it becomes clear why this search is so unpredictable. Even small washes or hidden canyon pockets can obscure evidence. The landscape itself works against anyone trying to locate her.

Not if they ain't gone out like a bunch of idjits and spoiled the ground... Any decent tracker would be able to see where folks went - especially once they are out and away from city folks... Tie him to a decent dog, one good for body searches, and you have a guided missile.

But more than likely they've had everybody and their grandma out doing searches and spoiling the sign. That's how this sort of thing goes. They always call in the trackers way too late.