A deranged art teacher allegedly filmed himself stabbing three people — killing one of them — just hours after he had been giving out Halloween candy to trick-or-treaters, according to authorities

Matthew Regnier, a 33-year-old instructor at Monument Academy in El Paso County, Colorado was found “fully naked and bloodied” and holding a 2-year-old child when police responded to a domestic dispute call at a home in Colorado Springs on Friday night.

The young child was “present, watching and crying” the horrific attack, according to an affidavit.

Police found three people with severe stab wounds at the residence — including the 2-year-old child’s uncle, who died from his wounds in the hospital.

Two women were treated for life-threatening injuries.

The victims’ relationship to Regnier was

See Full Page