GREENE COUNTY, Mo. – A Republic teenager accused of stabbing an elderly woman to death in 2016 has pleaded guilty to second-degree murder and was sentenced to life in prison.

Trystan T. Westrip was 16 when he killed 80-year-old Mary Shisler at her home near Strafford.

He was charged with first-degree murder, armed criminal action, first-degree tampering, and second-degree attempted arson after being certified to stand trial as an adult in 2017. Under a plea agreement, he pleaded guilty to murder in the second degree and armed criminal action. The other charges were dismissed.

Trystan T. Westrip

On Thursday, May 12, 20222, he was sentenced to life in prison for the murder and 10 years for ACA, to be served concurrently.

According to court documents in the case, authorities went to Shisler’s home near Strafford after neighbors reported a suspicious green vehicle in Shisler’s driveway. Shisler’s vehicle was also missing.

A neighbor entered through the back door of Shisler’s home – which was open – and smelled gas accompanied by a gas heater and burner to a stove both turned on. The neighbor turned off the appliances and called the police, according to a probable cause statement.

Deputies found a bottle of lighter fluid that had been slashed as well as a match sticking up inside a wad of toilet paper. A small amount of blood was also spotted in the home.

After running the VIN number to the suspicious vehicle, deputies confirmed it belonged to Westrip, who was considered a runaway.

Missouri Highway Patrol later found Shisler’s vehicle in Marshfield where they found Westrip to be the driver.

Westrip made several comments to investigators, saying he killed an “old lady” and dragged her body into a field near her residence. He was transported to the scene and pointed where he left her body. Shisler was found dead, having suffered multiple stab wounds to her head.

During a post-Miranda interview, Westrip says he left his home on Oct. 21 after an altercation with his parents.

He says he was trying to drive to Canada but later decided his vehicle (the one found in Shisler’s driveway) would not make it that far north.

He spotted Shisler’s truck, stopped, and began speaking with Shisler, he told investigators.

She offered to buy him gasoline but he refused and they began to walk to the neighbor’s house together. This is when Westrip pulled a knife out of his pocket and stabbed Shisler in the temple at least twice, the court document states.

He told investigators he then lifted her body over a fence and into a field to conceal it. Shisler was not yet dead and Westrip stabbed her seven more times in the head.

Westrip then stole items from Shisler’s residence and wished to destroy the evidence. This is when he soaked the toilet paper with gasoline and lit a match.