Decades after Stephanie Jackson was gunned down in her own home, a “damning detail” could provide a clue to her killer. 

During a re-examination of Jackson’s case on Cold Justice, investigators honed in on one key aspect of the homicide that could suggest Jackson was killed by someone familiar with her Florida home, according to a preview of the Oct. 11 episode titled “Deadly Message.”

Cold case investigator Nancy McNally explained while doing a reconstruction of the crime that after Jackson was gunned down in her living room on the morning of Sept. 3, 1999, someone had locked the door to the house as they left using a “push button” lock incorporated into the handle. 

That small detail led prosecutor Kelly Siegler to ask, “So, as he’s walking out, what kind of effort does he have to take to lock the door?” 

“He doesn’t have any effort at all,” McNally replied. “He just grabs the door and pulls it behind him.” 

Siegler wondered out loud why a “real burglar” would take the time to lock the door after carrying out a murder, which prompted homicide investigator Abbey Abbondandolo to offer up his own theory of the case. 

“I think it’s a habit,” he said. “You walk out, you always lock it.” 

It was a theory that McNally also felt made sense, given her own personal experience. 

“I don’t know about you guys, but the older house I lived in had just had that lock on the handle,” she shared, “and it just became habit to push that button and as I came out and shut the door.”

To investigators, it suggested that whoever killed the beloved mother and grandmother had been familiar with the property. 

“The final damning detail is that the door was locked by the killer on their way out,” Siegler told producers. “Does that sound like something an unknown intruder or thief would do? Not really. It sounds more like someone who used to live here’s habit.”

That seemed to match with another aspect of the crime, revealed in a separate preview. After killing Jackson, the killer rifled through several purses sitting in the kitchen, but rather than take the $187 in cash found in one of the wallets, the attacker only left with a driver’s license belonging to Jackson’s daughter. 

As Abbondandolo saw it, “That’s just sending a signal.”

Could Jackson’s killer have been sending a message to her daughter? 

To find out more about the heartbreaking case, watch Cold Justice Saturday, Oct. 11 at 8/7c on Oxygen.