The parents of a gunman who killed a Pennsylvania state trooper and permanently disabled another eight years ago in an ambush of a police barracks have settled a lawsuit accusing them of partial responsibility.

Tiffany Dickson, widow of Cpl. Bryon Dickson II, and Trooper Alex Douglass had alleged that Eugene and Deborah Frein knew their son Eric was mentally unstable and dangerous before the September 2014 attack outside the Blooming Grove state police barracks.

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The Freins had vehemently denied responsibility.

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The Citizens' Voice of Wilkes-Barre reports that Douglass's attorney declined to reveal details of the confidential settlement but says his client is relieved it is over.