California ? Stinging from an acrimonious divorce, a man plotting revenge against his ex-wife dressed up like Santa, went to his former in-laws’ Christmas Eve party and slaughtered at least eight people before killing himself hours later.

Bruce Pardo’s ex-wife and her parents were believed to be among the dead. Investigators planned to return to the scene today and sift through the ashes of the home, which Pardo set ablaze using a bizarre homemade device that sprayed flammable liquid.

Pardo, 45, had no criminal record and no history of violence, according to police, but he was angry following last week’s settlement of his divorce after a marriage that lasted barely a year.

“It was not an amicable divorce,” police Lt. Pat Buchanan said.

Pardo chose to exact his revenge at the annual Christmas party his former in-laws held at their two-story home on a cul-de-sac in a quiet Covina neighborhood 25 miles east of Los Angeles.