A federal appeals court on Friday upheld the convictions of David Matusiewicz and his sister Amy Gonzalez, who were sentenced to life in prison in the nation’s first prosecution of cyberstalking resulting in death.

In a precedential decision, a three-member panel of the U.S. Court of Appeals for the Third Circuit affirmed sentences, as well as the constitutionality of the interstate stalking law that federal prosecutors used to convict the siblings, after their father, Thomas Matusiewicz, killed Matusiewicz’s ex-wife and her friend in the lobby the New Castle County Courthouse in 2013.