DOVER, Del. — A federal court has rejected the appeals of a Delaware man and his sister who were sentenced to life in prison in a landmark cyberstalking case involving the killing of the man's ex-wife.

In a 77-page ruling Friday, a three-judge appeals court panel in Philadelphia upheld the siblings' convictions for what prosecutors say was a three-year campaign of torment and stalking against Christine Belford.

Belford and her friend were fatally shot at a Delaware courthouse in 2013 by the defendants' father, Thomas Matusiewicz, who then shot himself.

David Matusiewicz and Amy Gonzalez were later convicted, along with their mother, Lenore Matusiewicz, who died in prison in 2016.

Prosecutors say the Matusiewicz family harassed Belford online in an effort to regain custody of the three children she had with David Matusiewicz.