SPRINGFIELD, Mo. (AP) – Prosecutors are seeking a life sentence without the possibility of parole for a southwest Missouri teenager accused of killing an elderly woman.

The Springfield News-Leader reports that 17-year-old Trystan Westrip is charged as an adult with first-degree murder and attempted arson in the October 2016 stabbing death of 80-year-old Mary Shisler.

A probable cause statement says Westrip told deputies he killed Shisler and showed them where he left Shisler’s body. Investigators allege he also said he tried to burn down the woman’s home.

Greene County prosecutors filed a notice on Dec. 19 indicating they will seek a true life sentence. Prosecutors must prove at least one aggravating factor when pursuing such a sentence.

A phone message left by The Associated Press for Westrip’s public defender wasn’t immediately returned Wednesday.