Arizona authorities say their Mexican counterparts were resoundingly mistaken when they publicly claimed recently that they found alive a woman who was feared slain after disappearing in 2024 – a turn of events that her sister has called “turmoil” and “heartbreaking”.

The case in question centers on Shayna Feinman, who was reported missing in rural Yavapai county, Arizona, in March 2024 at age 38.

Authorities believe she was walking to an acquaintance’s home when she was last seen – but she never arrived or returned to her dog, as the Arizona news outlet KSAZ reported. An ensuing search turned up Feinman’s car abandoned near where she had been staying with her boyfriend, Cavett Richards, according to the station.

Her wallet and identification reportedly were inside the vehicle, and her cellphone was ultimately recovered on nearby land.

Although Feinman had not been found, the Yavapai county sheriff’s office subsequently charged Richards as well as a man named William DalCerro with second-degree murder, conspiracy and concealing a corpse in connection with her disappearance. But the charges were dismissed, a $20,000 reward being offered for information as authorities kept investigating the case.

The secretariat for security and citizen protection in the Mexican municipality of Tijuana then delivered what initially appeared to be a startling update in Feinman’s case on Saturday, saying in a statement that she had been located in the city’s Encino neighborhood the previous day.

The statement from the secretariat had a picture of the woman sitting in front of a desk atop which was a missing poster with Feinman’s information. It asserted without elaborating that investigators had confirmed Feinman’s identity, noting that her physical characteristics matched those listed in her missing person report.

The woman had been put in protective custody while Tijuana authorities arranged for her to speak with the Feinman family and US consular officials, the statement said. The agency went so far as to post a link to its Saturday statement on a social media page belonging to Feinman’s sister, Kara.

But both Kara Feinman and the Yavapai’s sheriff’s office met the Tijuana officials’ statement with evident skepticism.

Kara told KSAZ in a story published on Monday that she was waiting for the Yavapai sheriff’s office “to know for certain” that Shayna had been found.

Though she acknowledged the woman in the picture released by Tijuana officials had “similar physical attributes” to Shayna, Kara struck a cautious tone, telling KSAZ: “I can only hope and pray [for] good news – but right now, we have to be realistic.”

Meanwhile, a sheriff’s office spokesperson told KSAZ that the agency was “aware of reports indicating that Shayna Feinman may have been located in Mexico” – but “at this time, the information remains unconfirmed”.

“There is insufficient evidence to verify her identity,” Yavapai sheriff’s office spokesperson Paul Wick added to KSAZ. Wick said the sheriff’s office was “actively investigating the matter” and would provide an update as soon as one could be “confirmed and … released”.

The Yavapai sheriff’s office published that update on Tuesday, when it said in a statement: “Today, US authorities confirmed to [office] detectives, utilizing physical evidence, that the individual located is not Shayna Feinman.”

The sheriff’s office alluded to prior media reports “regarding the alleged discovery of Shayna Feinman” that “were published without official law enforcement confirmation” – before saying its “detectives continue to work diligently with [her] family during this stressful time”.

Tijuana’s security and citizen protection secretariat did not immediately respond to a request for comment.

In an interview with the Guardian on Tuesday, Kara Feinman said she believed the confusion about her sister possibly being in Tijuana initially stemmed from at least one concerned citizen who became convinced that she was there and made that known on social media.

She described being guarded about that possibility, reluctantly opening her mind in light of the Tijuana secretariat’s claims – and then enduring cyberbullying online by users who harshly judged her for not reacting effusively enough to the ultimately false news that Shayna had been found alive.

As she processed the reality that the search for the truth about her sister’s disappearance continued, Kara Feinman said her hope now was for those passionate about such investigations to realize how harmful it can be “jumping to conclusions without having all of the information” and then directing harsh words at the people most affected by those cases.

“Words are stronger than people think, and kindness can go so far,” Kara Feinman said. “It’s been turmoil going through this.

“It’s heartbreaking. It’s terrible, and I don’t wish this on anybody.”