PROSECUTORS say they’ll seek the death penalty for the man they call a “methodical and merciless killer” who stormed through a California beauty salon and killed eight people.

Orange County District Attorney Tony Rackauckas said Scott Dekraai has been charged with eight counts of murder and one count of attempted murder.

Mr Rackauckas said the rampage was caused by a long-running custody dispute that Mr Dekraai had with his ex-wife, Michelle Fournier. She was killed in the shootings.

Mr Rackauckas said Dekraai, 41, arrived at the salon on Wednesday carrying three weapons and dressed in body armour. At one point he stopped to reload, then continued shooting.

“For almost two minutes Dekraai shot victim after victim, executing people by shooting them in the head and chest,” the district attorney said.

Mr Rackauckas said Mr Dekraai wanted revenge against his ex-wife, who he believed was interfering in the raising of their eight-year-old son.Ms Fournier had recently told friends and family and said in court documents that she feared for her safety as Mr Dekraai became more and more unbalanced.

Mr Dekraai suffered post-traumatic stress disorder from a 2007 tugboat accident that mangled his leg and left a colleague dead, but his marriage to Ms Fournier was falling apart before then.