LANCASTER, Pa. (WHTM) — Claire Miller, the 14-year-old Lancaster County teenager charged with killing her sister, Helen Miller, has plead not guilty and had her arraignment waived last week.

Defense attorney Robert Beyer has requested that a decertification hearing be held in county court regarding shifting Claire Miller’s homicide prosecution to juvenile court. Beyer also filed notice of potential insanity or mental health defense.

If successful, Miller could be out of custody by age 21.

Back in February, Lancaster County police were called to Miller’s home in Manheim Twp. after she called saying hysterically that she “killed her sister.” The Lancaster Co. Coroner confirmed Helen Miller, 19, died from multiple stab wounds, and that her case would be ruled a homicide. They also confirmed Helen had cerebral palsy.

In their home on Clayton Road on February 22, Manheim Twp. Police say Claire Miller attacked Helen while their parents were asleep inside the house. In a search warrant released, investigators say Claire told someone on the phone that she was having “suicidal and homicidal thoughts.”

On April 16, it was announced Miller’s case would be going to trial, and she’s being charged as an adult.