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NEW CASTLE COUNTY, Del. (CBS) — A Delaware man sentenced to life in prison in a landmark cyberstalking case has lost his appeal in federal court.

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In 2016, David Matusiewicz, along with his mother and sister, were the first people in the country convicted of cyberstalking resulting in death.

david matusiewiecz Court Upholds Life Sentence In Delaware Cyberstalking Case

Credit: CBS3

They allegedly harassed his ex-wife, Christine Belford, for years over a custody battle.

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In 2013, David’s father, Thomas, shot and killed Belford inside the New Castle County courthouse.

Belford’s friend also died.