What seemed like a major break Tuesday — when authorities detained a person for questioning — fizzled when the man was released hours later. The detainment followed another potential break earlier in the day when investigators released video footage showing a masked and apparently armed man at Nancy Guthrie ’s doorstep the night of her disappearance.

The overall lack of progress has generated pressure and questions for local and federal investigators who haven’t held a news conference in days. From the outside, it might seem like solving the case and finding the 84-year-old Guthrie is growing unlikely, but investigators may be further along than they let on.

It’s not uncommon for cases to seem dead in the water at the outset and still eventually get solved, said Mary Ellen O’Toole, a former FBI profiler who worked on the yearslong search for the “Unabomber.”

So how do investigators tackle cases like this?

The masked figure and the Unabomber

Surveillance footage released Tuesday showed a person on Guthrie’s porch wearing a ski mask, backpack and what looked like a holstered handgun.

It offered the best opportunity yet for the public to help identify the suspect, said O’Toole, thinking back to the hunt for Ted Kaczynski, known as the “Unabomber,” who was caught in 1996 after a yearslong search.

Kaczynski, who carried out a 17-year bombing campaign that killed three people and injured 23 others, wrote a manifesto that was published in The New York Times and The Washington Post before he was caught.

His brother recognized Kaczynski’s tone in the screed, tipped off the FBI, and Kaczynski was arrested in a cabin outside Lincoln, Montana.

Similarly, Luigi Mangione, who allegedly shot the CEO of UnitedHealthcare in New York, was arrested five days later when someone recognized him at a McDonald’s and called in a tip.

In Guthrie’s case, the release of the surveillance footage and Savannah Guthrie’s plea for the public’s help is the same strategy, O’Toole said.

Someone who knows the suspect may have noticed them acting unusual, such as not going to work, following the news closely or making offhand comments about the case.

If they recognize anything familiar about the masked person on camera, that could confirm their suspicions and lead them to tip off investigators, O’Toole said.

DNA and the University of Idaho murders

Investigators said DNA from blood on Guthrie’s porch matched her, and O’Toole said investigators will still be casing the area for DNA from a possible suspect, including hair or fingerprints, which have helped solve other cases.

Bryan Kohberger, the criminology student who sneaked into a home and stabbed four University of Idaho students to death in 2022, was arrested after trace DNA was found on a knife sheath left on one of the victim’s bed.

That DNA didn’t yield any results from standard law enforcement databases, so investigators turned to publicly available genealogy services, searching for possible relatives.

After homing in on Kohberger by tracking his car using surveillance footage near the crime scene, investigators got a Q-tip from the trash outside his family’s home and tested the DNA.

It matched the father of the person whose DNA was on the knife sheath.

Strange encounters and the Brown University shooting

In the days after a shooter killed two people at Brown University in 2025, investigators didn’t appear any closer to identifying the suspect.

When police eventually shared images of a person of interest, a man started posting on Reddit that he recognized the person and that police should look into a gray Nissan.

The source, named only as “John” in a police affidavit, told investigators that he’d bumped into a man in the bathroom and thought his clothing was “inappropriate and inadequate for the weather.” John saw him again outside acting nervous and jumpy near the Nissan.

John’s tip about the car helped identify the shooter, Claudio Neves Valente, six days later, leading investigators to a storage unit where he was found dead from suicide.

It’s unclear if John took the $50,000 reward for information that was offered in the case. The FBI is offering the same amount for information in Guthrie’s apparent abduction and hoping a tipster like John may come forward. The Pima County Sheriff’s Department said Wednesday that they have received nearly 18,000 calls since the day Guthrie was reported missing.

Connor Hagan, a spokesperson for the FBI, said in a previous statement: “Someone has that one piece of information that can help us bring Nancy home.”