The Greene County Prosecutor’s Office plans to seek a life sentence without the possibility of parole for the Republic teenager accused of killing an 80-year-old woman.

On Dec. 19, prosecutors filed a notice to go after a true life sentence for 17-year-old Trystan Westrip, who is accused of killing 80-year-old Mary Shisler at her home near Strafford in October 2016.

A life sentence without the possibility of parole is the most severe sentence Westrip could face, since he was a 16-year-old juvenile at the time of the homicide.

To go after a life sentence without the possibility of parole for a juvenile, prosecutors must prove at least one aggravating factor. In their December motion, prosecutors listed three factors they believe apply to this case:

  • The defendant inflicted severe pain on the victim for the pleasure of the defendant or for the purpose of inflicting torture.
  • The defendant killed the victim after she was otherwise rendered helpless by the defendant.
  • The first-degree murder was committed against a witness or potential witness to a past or pending investigation or prosecution.

Westrip has been charged with first-degree murder, armed criminal action, tampering with a motor vehicle and attempted arson.

A hearing was scheduled for Tuesday in the case, but it was postponed.

Authorities believe Westrip killed Shisler on Oct. 21, 2016 at or near her home in the 8300 block of North Farm Road 223.

Greene County deputies were called to Shisler’s home after a neighbor noticed Shisler’s truck was gone and her home might have been burglarized.

Authorities say Westrip was stopped in Shisler’s truck a few hours later in a neighboring county.

According to a probable cause statement in the case, Westrip told deputies he killed an “old lady” and then showed them where he left Shisler’s body.

The medical examiner later testified that Shisler was stabbed in the head, but she likely lived for a few hours after the attack.

Westrip ran away from home on Oct. 21, 2016, after an argument with his parents. The statement says he planned to go to Canada, but he did not think his vehicle would make it.

Westrip allegedly told investigators he drove around until he spotted Shisler’s house and vehicle. He pulled into the driveway.

The statement says Shisler offered to help Westrip get gasoline and let him borrow her phone.

Westrip told investigators that Shisler then suggested they walk to a neighbor’s house to get help, the statement says. When Shisler was in front of him as they walked along Farm Road 223, Westrip told investigators he retrieved his knife and stabbed her in the left temple, the statement says.

According to the statement, Westrip said he lifted Shisler’s body over a fence, dragged her body into a field and stabbed her approximately seven more times in the head.

Westrip said he went back to Shisler’s house, stole several items, tried to set the house on fire and then left in her truck, according to the statement.

Westrip is being represented by the same division of the Missouri State Public Defender’s Office that represents people facing the death penalty.