SALINA, Kan. (AP) — The trial for a 15-year-old Kansas girl accused of killing her sister will be delayed until March.

A Saline County Court judge agreed Friday to delay the first-degree murder trial of Sierra Niehaus, who had been scheduled for trial later this month. She is being tried as an adult.

Prosecutors allege Niehaus stabbed her 13-year-old sister, Galazia, to death at the family’s rural Saline County home on Aug. 1, 2014.

The Salina Journal reports Niehaus’ attorney asked for more time to prepareor the trial.

The new trial date is March 21.