People magazine investigates the murder of Sarah Greenhalgh

On the morning of July 9, 2012, black smoke billowed into the sky above Upperville, Virginia, when a fire broke out in a small cottage, engulfing it in flames.

Firefighters who arrived at the scene were shocked to find a woman’s body in the bedroom. Even more shocking was the fact that the woman, as established by the authorities, did not die in the fire, but from a gunshot wound.

The murder of the woman found in the cottage, 48-year-old Sarah Libby Greenhalgh, has shaken the normally quiet horse town, as well as her co-workers Winchester Star, where she worked as a reporter, and her family.

Greenhalgh’s mysterious murder is revealed in the second episode of the season premiere People magazine is investigating on Monday, October 28

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

When Greenhalgh’s mother, 95-year-old Sara Lee Greenhalgh, learned her daughter had been killed, she couldn’t believe it.

“It’s just almost impossible to get your head around that word,” she says in the episode. “I just can’t understand that Sara will be killed. Who would do that?”

The Fauquier County Sheriff’s Office was looking for evidence of who wanted Sarah dead.

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

“It was in the form of a Facebook post that she wrote hours before she died,” Baker says.

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

Want to keep up with the latest crime news? Subscribe to Free PEOPLE True Crime Newsletter for breaking crime news, coverage of ongoing trials and details of intriguing unsolved cases.

“Sunday night to Monday morning was an important question that narrows the time frame to when this murder would have occurred,” Hartman says.

That Facebook post, as Greenhalgh’s former colleague Melissa Boughton says in the episode, “was pretty cryptic.”

It read: “I will sleep with the window wide open. Now if the bat-sh– crazy guy will just leave me alone… I’ll get some much needed rest because tomorrow is Monday and I’ve got a ton of work to do.”

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

Hartman adds, “That social media post was very telling. It was very disturbing. So obviously we wanted to know who the crazy guy was.”

That “boy” turned out to be John Kearns, then 50, a coachbuilder who had dated Greenhalgh before her death and had been seen arguing with her the night before, police said.

The Fauquier County Sheriff’s Office named him a suspect in testimony that noted “significant damage” to his fists, which he said was from martial arts training. The affidavit alleges that Kearns deleted emails to and from Greenhalgh.

But no evidence of arson or the “violent struggle” Greenhalgh was involved in before her tragic death was found on him 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 airs on Max. The episode follows the season premiere People magazine is investigatingepisode titled “The Boogeyman,” about the murder of Florida girl Jessica Lunsford, which airs at 9 p.m.