Paul Caneiro, 51, was charged with four counts of murder as well as arson and two weapons violations in the deaths 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.

FREEHOLD, N.J. — A New Jersey tech executive was charged Thursday with killing his brother and the brother's family as a result of a business dispute and then setting fire to their mansion and his own 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 deaths 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.

"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 — he and his brother jointly ran in Asbury Park, the prosecutor said. He declined to elaborate, saying the investigation was incomplete.

Caneiro had already been under arrest on a charge he set fire to his own home 10 miles away in Ocean Township, while his wife and two daughters were inside. The second fire was a "ruse" intended to make it appear the extended family was a target, the prosecutor said. He said there was no evidence he intended to kill his own family. They escaped without injury.

Caneiro's attorney, Robert Honecker, said he was on his way to the Monmouth County Jail to discuss the case with his client and would comment on the latest charges afterward.

He had previously said Caneiro was innocent and "devastated by the news of his brother and his family's deaths."

A criminal complaint said both a gun and a knife were seized from Caneiro, who is scheduled for a court appearance Friday morning.

"This one is the most brutal case I've seen in my experience here," the prosecutor said.

Keith Caneiro was shot numerous times on the lawn of his mansion in Colts Neck, an affluent horse country town that's home to rock star Bruce Springsteen, and where former "Daily Show" host Jon Stewart and his wife operate an animal sanctuary.

Jennifer Caneiro was shot and stabbed, and the two children, 11-year-old Jesse and 8-year-old Sophia, were stabbed repeatedly, the prosecutor said, disclosing for the first time how the three died.

According to the prosecutor, Paul Caneiro shot his brother on the lawn of the mansion, went inside and killed the rest of the family, and then set a fire in the basement in the early morning hours of Nov. 20. He then returned to his own home and set gasoline ablaze outside both ends of the building.

The prosecutor said the fire at Paul Caneiro's house was set to destroy evidence he had brought there from the crime scene, but also had another purpose.

"That fire was a ruse to make it appear as if the overall Caneiro family was somehow targeted," Gramiccioni said.

Investigators found no evidence of anyone else being involved in the crime, he said.

The fire in Paul Caneiro's home was reported at 5 a.m. But prosecutors allege the Colts Neck fire was set before that, even though the mansion blaze was not reported until about 12:30 p.m. The prosecutor said the mansion fire smoldered in the basement for hours before being discovered.