FREEHOLD, N.J. • A New Jersey technology executive was charged Thursday with killing his brother and the brother’s family over a business dispute, and then setting fire to their mansion and his house in an attempt to cover up the crimes.

Paul Caneiro, 51, was charged with four counts of murder, as well as arson and two weapons violations, in the death of his 50-year-old brother, Keith, along with Keith’s wife, Jennifer, and their two children, at their Colts Neck estate, about 50 miles south of New York City.

They were shot, stabbed or both.

“This one is the most brutal case I’ve seen in my experience here,” said Monmouth County prosecutor Christopher Gramiccioni.

Caneiro’s motive “was financial in nature,” stemming from two businesses — a computer systems company called Square One and a pest control business — that he and his brother jointly ran in Asbury Park, the prosecutor said. He declined to elaborate.

Keith Caneiro had some upcoming job interviews planned after getting his master’s degree this year, according to Brian Bott, who owns a fitness studio where he worked out.

Bott did not know whether he planned to keep working with his brother if he got a new job.