Investigators are using Nancy Guthrie's pacemaker to track signals, hoping for a breakthrough. Photo / Getty Images
In the US, as the search for Nancy Guthrie stretches into its third week, investigators are turning their attention to a half-dollar-size device they hope could lead to a breakthrough in the case: the 84-year-old’s pacemaker.
The heart-rate-regulating device was disconnected from an app on Guthrie’s phone at 2.28am on February 1, shortly after doorbell camera footage detected a person on her front porch. The app on Guthrie’s phone, which was left at her home in Tucson, picked up data transmitted from her pacemaker via Bluetooth. But pacemakers still attempt to transmit that data, even if someone is separated from their mobile device, according to digital forensics experts.
With that in mind, investigators are turning to novel technology to help detect any signals still being transmitted by Guthrie’s pacemaker. Her device has six or seven years of its decade-long battery life remaining, Pima County Sheriff Chris Nanos said, citing information provided by the manufacturer. Nanos declined to identify the manufacturer but said the company has been working with the FBI and engineers to figure out ways to track signals from Guthrie’s device.
The manufacturer is just one of several companies that have offered to assist investigators, Nanos said. Alongside the pacemaker company, Nanos said, Apple and Google, which sells the Nest doorbell camera Guthrie used, have also contacted him.
“Everybody has come up and said, ‘What do you need, Sheriff?’” Nanos said.
For weeks, investigators have run into challenges while collecting evidence, leading to delays in sharing information about the alleged abduction with the public. It took 10 days for Nanos’ department and the FBI to release the first images of a suspect, which were retrieved through the aid of private companies because Guthrie did not have a subscription attached to the doorbell camera that would have allowed more immediate access to the video storage.
Tips flowed in after the videos were released, but detectives still have not publicly named a suspect, and they have not found a match for DNA recovered from other evidence around Guthrie’s home. Nanos said his team is looking at key elements of the doorbell camera footage – namely what the suspect was wearing, including a backpack, mask and holster – to help identify them.
Still, such hurdles in the case have pushed law enforcement to consider new ways to leverage technology, the pacemaker chief among them, Nanos said.
Investigators and the Guthrie family implored potential abductors to consider Guthrie’s health conditions and her reliance on daily medications early after her disappearance. Today show co-host Savannah Guthrie and her siblings said in video messages posted to social media that their mother’s heart was “fragile” and that she needed medicine to survive.
Rishi Anand, a cardiologist at Holy Cross Health in Fort Lauderdale, Florida, said most modern pacemakers are equipped to connect via Bluetooth to an accompanying device, which receives information about the pacemaker’s condition and the user’s heartbeat. That device then sends the data to a doctor’s office, he said, but pacemakers can’t connect to the internet or send geolocating information.
But Nanos said once investigators learned pacemakers still “ping every so often,” even when disconnected from a mobile device, they immediately began examining ways to detect those signals.
This week, officials used experimental “signal sniffer” technology mounted to a helicopter to try to locate any pacemaker signals, CBS News reported, citing unnamed law enforcement officials. That tool was developed by David Kennedy, a former National Security Agency hacker who has done cybersecurity work for government agencies through the two firms he helped found, Binary Defence and TrustedSec.
Kennedy said the tool uses signal amplifiers and antennas that attach to aircraft, such as helicopters or drones. The aircraft can be flown over an area of interest to detect possible signals from pacemakers or other data-transmitting devices.
A major challenge, Kennedy said, is that the aircraft needs to be within range at the exact moment a signal is emitted. That requirement is complicated by the fact that it’s unclear how large an area investigators will be searching.
Nanos and his department declined to comment on whether they’re using those tools in their investigation. The FBI did not immediately respond to questions about the technology.
Kennedy cautioned that trying to detect a missing person’s pacemaker’s signals would “require a pretty monumental effort”. Jim Jones, a George Mason University professor and expert on cybersecurity and digital forensics, said while such efforts are a “long shot”, they’re worth trying.
“It’s a bit like looking for a small object in your backyard with a microscope,” Jones said. “You have to be right on the right spot at the right time to be able to detect it.”
Nanos said investigators are also trying to match DNA recovered from a glove found near Guthrie’s home to genealogy databases. Officials said Tuesday that DNA samples taken from the glove did not match anyone in the FBI’s database or the samples taken from Guthrie’s home. The sheriff’s office declined to specify the number of DNA profiles being analysed by labs.
Law enforcement is also working with retailers to pull data on sales for the backpack and the mask the suspect was seen wearing in the doorbell camera footage. The backpack model is sold exclusively by Walmart, and Nanos said the retailer’s management is coordinating with law enforcement to determine who might have purchased it. Detectives are also visiting gun stores to see if anyone recognises the holster seen in the video, he said.
“Every piece of evidence will be looked at,” Nanos said.
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