'He Planned To Kill': Missing Indiana 15-Year-Old Found Murdered In Backyard

Jessica Oesterle didn't think much of it when her 15-year-old daughter, Alexis Oesterle, wasn't at their Rockport, Indiana, home on the morning of Nov. 2, 2009.

As her daughter was widely regarded as a "social butterfly" and "very independent," Jessica assumed that she had gone out and spent the night with friends, and it wasn't unlike her to forget to leave a note letting her parents know of her plans.

But as the day went on and there was still no word from Alexis, Jessica as well as Ryan Shelby, her husband and Alexis' stepfather, began to worry. The couple reached out to several of Alexis' friends, who said they hadn't heard from Alexis in the past 24 hours.

Ryan suggested they call 911 to report her missing, and former Spencer County sheriff's deputy Jason Dunsworth responded to the call.

Dunsworth began a preliminary investigation, and he noticed Alexis' window was partially opened. Upon further inspection of the backyard, he made a gruesome discovery: Alexis' body. Her throat had been slit and her body had been stabbed.

"The police escorted us out to the car, and Ryan and I got in there, and I just kept repeating, 'It's not my daughter, it's not my daughter, it's not my daughter' about a hundred times. In my heart, it wasn't her, it couldn't be her," Jessica told "Criminal Confessions," airing Saturdays at 6/5c on Oxygen.

Jessica and Ryan were interviewed separately by investigators, and initially, both of their stories matched up.

Ryan had called Jessica at around 9:40 p.m., claiming his car had broken down while driving home from his parents' house and that he needed her to pick him up.

As she prepared to leave, an unfamiliar black truck pulled up in the driveway that neither Alexis nor her mother recognized. Jessica, however, had to retrieve Ryan and left Alexis at home.

By the time she arrived at the agreed destination, Ryan was nowhere to be found, and she called him from a payphone. Ryan said his car had started working again, and they regrouped at the house —  where both the truck and Alexis were nowhere to be seen.

Alexis Oesterle

Hours after finding Alexis' body, investigators tracked down the owner of the pickup, who was friends with Alexis. He informed detectives that he arrived at her house to hang out just as Jessica was leaving. He and Alexis were talking inside his truck when a shadowy figure walked through the yard.

"Alexis told me, she goes, 'I'll be right back,'" the friend told detectives.

When she returned, she had a knife in her hand. Alexis claimed the man was Ryan, and that the two got into an argument because he left her baby sister, Aria, at his parents' house.

Just a few months before the murder, Ryan had taken off with Aria for several weeks, causing strife within the family. Jessica and Ryan reconnected and attempted to fix their marriage, but Alexis still had animosity toward her stepfather.

"And then she said, 'I'm so mad, I could stab him,'" the young man told detectives. 

He added that he was able to convince Alexis to give him the knife before she returned to the house.

After hiding it securely in his truck, he drove away.

Indiana State Police first sergeant Robert Gardner circled back to Ryan to question his version of events. Ryan denied that his stepdaughter pursued him with a knife and that he did anything to harm her, but he did admit that he arrived at his house much earlier than he originally told law enforcement.

"If he's lying about these little things that don't matter, what else is he lying about that is a big thing that does matter?" Gardner asked.

The next day, both Ryan and Jessica agreed to take a polygraph test as a secondary search was performed on the residence in hopes of uncovering the murder weapon and any other evidence that connected Ryan to Alexis' death. 

Before conducting his polygraph test, Ryan informed detectives that he had been wearing black steel-toed boots with a buckle on the ankle the night of Alexis' death — not the work boots he wore to the station. Shortly after Gardner tipped off investigators about the boots, Detective Troy Fischer found a match in Ryan's bedroom closet.

"I start looking at them in the light, and I see what I think is blood spatter on the top of the boot," Fischer said.

Gardner then sent for a crime scene investigator, who confirmed that tissue remains and blood were on the boot. Back at the station, it was determined Ryan failed the polygraph test on the questions regarding whether or not he caused Alexis' death.

"I tell people all the time this machine has no conscience; it doesn't care if it lies or not. But a human does have a conscience, and they do care if they lie or not. That's why the instrument is telling us that you've lied," Gardner said.

In order to obtain a confession from Ryan, Gardner employed interview techniques that would make him feel safe giving an honest account of what happened the night of his stepdaughter's death.

"Ryan, there's two types of people ... guys that make a mistake and cold-blooded murderers. Which one are you?" Gardner asked Ryan.

Jessica Oesterle and Ryan Shelby

Ultimately, Captain Robert Priest entered the interrogation room to speak with Ryan. They presented him with the overwhelming evidence against him, and Ryan, overcome with emotion, admitted that Alexis came at him with a knife.

"I slit at her ... I just kept stabbing," Ryan confessed. He also admitted that he dragged her body behind the shed in the backyard, a key detail that investigators had not made public at that time.

"He's telling me things that only the killer would know," Priest said. "It's going to help demonstrate Ryan's culpability to the crime in a court of law."

After the interview, Ryan was formally arrested. Footage from the interview room shows him leaving with Priest and Gardner, who is heard saying, "You did the right thing. You did the right thing."

As Jessica sat for her polygraph test, Sergeant Christopher Cecil was tasked with informing her that her husband had been arrested for confessing to the murder of her daughter.

"If I thought that Ryan was capable of hurting her, I would've never stayed," Jessica told "Criminal Confessions." "I wouldn't allow somebody around that I thought was gonna cause harm."

While the murder weapon was not recovered, security footage from a nearby storage facility caught Ryan parked and later speeding out of the area without headlights on.

"He lured Jessica Shelby away from the house, he parked away from the house, he walked out in the shadows ... Somebody who was not planning to kill somebody would not take those steps," Priest said.

"This was not an accident, this was not self-defense," Cecil added. "He planned to kill Alexis."

Ryan was found guilty of murdering Alexis in 2012 and was sentenced to 55 years in prison. He appealed his verdict, but the conviction was upheld as of April 2013.

To hear more about the case, watch “Criminal Confessions” now on Oxygen.