It is no bigger than a sliver of shadow.
But that faint bulge - a subtle band pressing against a gloved pinky finger - is fast becoming one of the most talked-about clues in the chilling disappearance of Nancy Guthrie.
Three weeks into an increasingly frantic search for the 84-year-old mother of NBC 'Today' co-anchor Savannah Guthrie, investigators are zeroing in on a detail that could provide a much needed break in the case: a pinky ring apparently worn by the masked man caught on doorbell camera footage the night she vanished.
The grainy video, recorded on the porch of Guthrie's $1 million ranch-style home just north of Tucson, Arizona, shows a man in a ski mask, backpack, jacket and gloves.
He approaches the front door and reaches toward the camera with his right hand. In that split second, a band-shaped imprint appears beneath the glove on his little finger.
Small Clue Could Prove Crucial in Kidnapping Probe
The Daily Mail spoke with three former law enforcement officials who agreed that even such a small detail could help narrow the hunt for the suspect in what authorities are investigating as an alleged kidnapping.
At the very least, they said, the presence of a ring on the pinky could help detectives prioritize leads.
In a case flooded with tips - more than 28,000 phone calls between February 1 and 16, a 54 percent spike over the same period last year - triage is critical, said Lance Leising, an Arizona-based former FBI supervisory special agent.
'If a tip identifies someone who matches the description and investigators see a pinky ring in social media posts, that would make that tip a higher priority and more resources would be applied,' he added.
Leising cautioned that he was not certain the video is definitive. The footage is grainy. The lighting is poor. What appears to be a jewelry band could be a fold in the glove.
But in a case like this, he added, every detail is 'useful.'
Distinctive Pinky Ring Emerges as Key Identifier
Pinky rings are not common - and that makes them distinctive.
Gregg Etter, a criminology professor at the University of Central Missouri and a 29-year law enforcement veteran, called the ring a potential 'trait' that could move a suspect to the top of the list.
When detectives are chasing down leads and perhaps a dozen individuals merit closer scrutiny, he said, the man known to wear a ring on his right pinky suddenly becomes more interesting.
It is not proof. It is not probable cause. But it is a filter.
'Anything can be useful as a clue,' added Daniel Brunner, a 29-year veteran FBI special agent. 'Nothing can be not considered.'
The focus on that tiny band of shadow comes as the search for Nancy Guthrie stretches into its 18th day with no arrests.
Guthrie was reported missing on February 1 after spending the previous night with family.
Blood was later detected on the porch of her secluded home in the upscale Catalina Foothills community.
The FBI has said the suspect appears to be about 5 feet 9 inches tall with a medium build.
Every frame of the porch video has now been pored over by investigators - and by legions of online sleuths.
The moment the masked man reaches up to tamper with the camera has become a tipping point in the case.
Reddit threads and Facebook groups have exploded with theories. Some users claim the bulge resembles a simple wedding band. Others argue it looks thicker - perhaps a signet ring.
Some have attempted to estimate the height of the ring's setting from the distortion of the glove fabric.
Sheriff Acknowledges Ring Speculation in Investigation
Pima County Sheriff Chris Nanos has acknowledged the speculation.
'I look at the same photo you look at and I get. I see it. I see,' Nanos told NBC News this week.
He said investigators would 'analyze' the clue while noting that it remains an area of 'speculation.'
Still, speculation can guide inquiry. Leising suggested that the ring could even point investigators toward specific organized groups known to wear pinky rings.
'If you identify organized groups that wear a ring on the right pinky, that would be a good group to investigate and identify members,' he said.
Historically, pinky rings have been associated with organized crime figures - famously worn by mob boss John Gotti, as well as fictional gangsters like Tony Soprano and Michael Corleone.
Modern criminal organizations, including some Central American drug cartels, are known for conspicuous jewelry and displays of wealth.
Etter said he was unaware of any strong current preference for pinky rings among major gangs, but acknowledged that jewelry can serve as a symbol of affiliation or status.
And it is not just gangsters. Members of fraternal organizations such as the Freemasons have long worn pinky rings.
Investigators Pursue Even Remote Leads
Aristocratic families have passed down signet rings bearing crests for generations.
Engineers in North America sometimes wear simple iron or steel bands. Geologists sport silver rings. Graduates of the Canadian Institute of Forestry are known to wear distinctive bands.
It is a wide net. Perhaps too wide. But in a case where false dawns have already come and gone, investigators appear willing to chase even remote possibilities.
On Saturday, hope briefly flared when a Special Weapons and Tactics team raided a home near Nancy Guthrie's residence.
Authorities searched a grey Range Rover and detained the driver. Multiple individuals were questioned. No arrests were made.
Another potential breakthrough emerged when law enforcement recovered a glove near Guthrie's property that appeared similar to the one worn by the masked man in the video.
But Sheriff Nanos later said the glove yielded no new leads. It failed to match the Combined DNA Index System, the national database of DNA profiles.
The investigation is being led by the Pima County Sheriff's Office alongside the FBI.
Sources have told TMZ that authorities are considering the possibility that Nancy Guthrie was taken across the border.
Sheriff Maintains Hope Without Proof of Life or Death
The sheriff's office has acknowledged reports of coordination with Mexican authorities but declined to confirm specifics.
Through it all, the question looms: is Nancy Guthrie still alive?
'They ask me, do I have proof of life? I ask them, is there proof of death?' Nanos said earlier this week.
For Savannah Guthrie, the agony is public and relentless. In an Instagram video posted Sunday, she appealed directly to anyone with information.
'It is never too late to do the right thing,' she said. 'And we are here. And we believe in the essential goodness of every human being, that it's never too late.'
Back on the porch of that Catalina Foothills home, investigators are still studying the footage.
A masked man. A gloved hand. A shadow on a pinky finger. In a case defined by absence - no body, no arrest, no clear suspect - that small, stubborn detail may yet prove decisive.