People Magazine investigates the murder case of Sarah Greenhalgh

On the morning of July 9, 2012, black smoke billowed through the air above Upperville, Virginia, when a fire broke out in a small house, causing it to burst into flames.

Firefighters who arrived on the scene were shocked to find the body of a woman in a bedroom. Even more shocking, authorities determined, the woman did not die 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 middle of the horse world, as well as her colleagues across the country. The Winchester Star, where she worked as a reporter, and her family.

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

The titled episode airs on Investigation Discovery/ID at 10/9c and streaming on Max. ‘A Story to Die For’ chronicles 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, heard her daughter had been killed, she couldn’t believe it.

“It’s almost impossible to understand that word,” she says in the episode. ‘I just can’t imagine Sarah being murdered. Who would do that?”

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

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

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

The episode featured retired Fauquier County Sheriff’s Office Sgt. James Hartman, who was also the department’s public information officer, said Greenhalgh had last posted on social media around 11 p.m. the night before she was found dead around 8 a.m. the next morning, a Monday.

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“Sunday night into Monday morning was the big question that narrows the time frame to determine when this murder might have occurred,” Hartman said.

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

It said: ‘I’m going to sleep with the window wide open. If Bat-sh… that crazy boy would just leave me alone… I’ll get some much needed rest because tomorrow is Monday and I have a lot of work to do.”

Boughton says: “The post was, as far as we know, the last thing Sarah ever wrote.”

Hartman added: “That social media post was telling. It was very worrying. So we obviously wanted to know who the crazy guy is.

That “boy” turned out to be John Kearns, then 50, an auto body worker, who was in a relationship with 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, which noted “significant injuries” to his fists that he said were the result of martial arts training. The affidavit alleges that Kearns deleted email messages to and from Greenhalgh.

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

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

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