A Pequea Township woman was sentenced to five years of probation, the first six months of which will be served in Lancaster County Prison, after submitting a plea of guilty but mentally ill for killing her grandmother in 2023.

Judge David Ashworth sentenced Shasta Marie Sigman, of the first block of West Boehms Road, after she pleaded guilty but mentally ill to involuntary manslaughter Nov. 27.

Once paroled, Sigman, 25, will serve her probation at a residential mental health treatment facility in Armstrong County.

Assistant District Attorney Elizabeth Lapp, who prosecuted the case, said the negotiated plea came after “extensive input” from the victim’s family and was the “best outcome” for everyone as they move forward with their lives.

Speaking to the court, Sigman said she wanted to use her sentence to “try to focus on (herself)” and get her life in order.

Judge Ashworth warned Sigman not to harm anyone else in treatment or else she could find herself back in prison.

A mental health evaluator determined that Sigman suffers from an intellectual disability, with her attorney explaining that Sigman can understand that her actions were wrong but is unable to comprehend their consequences.

Sigman shoved her 82-year-old grandmother in the chest, causing her to fall to the floor and strike her head against the wall at a residence in the 100 block of Sigman Road, Providence Township in August 2023. The victim lost consciousness and stopped breathing as a result of being pushed by Sigman.

The victim was taken to Lancaster General Hospital where she died as a result of the fall. An autopsy concluded that the victim died as a result of a traumatic neck injury and her death was ruled a homicide.

In an interview with police, Sigman said she had argued with the victim earlier in the day over wanting a hamburger for lunch – a request the victim denied.

When Sigman again requested the hamburger she pushed the victim with “her full force,” she told police, adding that she considers herself “a strong person.”

Sigman told investigators “I don’t know the concept of ‘no’ and that’s the whole problem; it’s hard for me.”

A witness to the assault told police Sigman never attempted to assist the victim after she pushed her, instead sitting down and saying “she’ll be OK; she’s fine.”

Trooper Noah Robinson of Pennsylvania State Police filed the charges.