Reporter Sarah Greenhalgh Was Murdered After Her 'Cryptic' Facebook Post. But Who Did It?

On the morning of July 9, 2012, black smoke billowed through the skies above Upperville, Va., when a fire broke out at a small cottage, engulfing it in flames.

Firefighters who rushed to the scene were shocked to find the body of a woman in a bedroom. Even more shocking was that the woman, authorities determined, didn’t perish in the fire, but from a gunshot wound.

The murder of the woman found in the cottage, Sarah Libbey Greenhalgh, 48, rocked the usually serene town in the midst of horse country, as well as her co-workers at The Winchester Star, where she worked as a reporter, and her family.

Greenhalgh’s mysterious murder is featured on the second episode of the season premiere of People Magazine Investigates on Monday, Oct. 28.

Airing on Investigation Discovery/ID at 10/9c and streaming on Max, the episode, titled. “A Story to Die For,” details what happened before the talented reporter and photographer was found dead — and in the months and years that followed as police tried to figure out who took her life.

When Greenhalgh’s mother, Sara Lee Greenhalgh, 95, learned that her daughter was murdered, she couldn’t believe it.

“It’s just almost impossible to get my head around that word,” she says in the episode. “I just can’t fathom that Sarah would be murdered. Who would do that?”

The Fauquier County Sheriff’s Office looked for clues as to who would have wanted Sarah dead.

“One of the biggest breaks in this case came from Sarah herself,” says PEOPLE senior writer K.C. Baker in an exclusive clip from the season premiere.

“It came in the form of a Facebook post she wrote hours before her death,” says Baker.

In the episode, retired Fauquier County Sheriff’s Office Sgt. James Hartman, who was also the department’s public information officer, said Greenhalgh last posted to social media around 11 p.m. the night before she was discovered dead at around 8 a.m. the nexdt morning, a Monday.

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“Sunday night to Monday morning was the big question that narrows down the timeframe to determine when this murder would have occurred,” Hartman says.

That Facebook post, Greenhalgh’s former fellow reporter Melissa Boughton says in the episode, “was fairly cryptic.”

It said, ​​“Going to be sleeping with the window wide open. Now if bat-sh– crazy boy would just leave me alone … will get some much needed rest because tomorrow is Monday and I got a ton of work to do.”

Boughton says: “The post was, to our knowledge, the last thing that Sarah ever wrote.”

Adds Hartman: “That social media post was very telling. It was very concerning. So obviously we wanted to know who batshit crazy boy is.”

That “boy” turned out to be John Kearns, then 50, an auto body worker, who was dating Greenhalgh before her death and who had been seen arguing with her the night before, police said.

He is named as a suspect in the affidavit by the Fauquier County Sheriff’s Office, who observed “significant injuries” on his fists, which he said were from martial arts training. The affidavit alleges that Kearns had deleted email messages to and from Greenhalgh.

But no evidence of arson or the “violent struggle” that Greenhalgh was in before her tragic death was found on his person or in his Jeep, the affidavit says.

Kearns, 62, of Virginia, has never been charged. He declined to comment to PEOPLE.

People Magazine Investigates: A Story to Die For, airs on Monday, Oct. 28, at 10/9c on Investigation Discovery/ID and streams on Max. The episode follows the season premiere of People Magazine Investigates, an episode titled, “The Boogeyman,” about the murder of Florida girl Jessica Lunsford, which airs at 9/8c.