A 16 year old Kansas teenage girl, Sierra Neihaus has been sentenced to 16 years in prison for fatally stabbing her 13 year old younger sister to death. Sierra Neihaus was sentenced on Tuesday in Saline County, Kansas. Sierra Neihaus was 14 at the time she fatally stabbed her 13 year old sister, Galazia Neihaus, at the family's rural home on August 1, 2014.