A Monmouth County, N.J., man was charged Thursday with killing his younger brother and sister-in-law, along with their two young children, last week before setting fire to the victims’ $1.5 million estate in Colts Neck in a dispute over finances, officials said.

Paul Caniero, 51, then returned to his own home in Ocean Township and set it on fire to cover up evidence and make it appear that the deadly attack at his brother’s home was part of a larger plot against their family, said Monmouth County Prosecutor Christopher J. Gramiccioni.

Caneiro was taken into custody the day after the fires.

Early on Nov. 20, Caneiro shot and killed Keith Caneiro, 50, outside the latter’s home, Gramiccioni said. The suspect also shot and stabbed his sister-in-law, Jennifer Caneiro, 45, and stabbed his nephew and niece, Jesse, 11, and Sophia, 8, inside the house. Paul Caneiro then set a fire in the basement that smoldered for hours before flaring up, the prosecutor said.

Prosecutors say Paul Caneiro set another fire at his own home about 5 a.m. It was not until about seven hours later that firefighters responded to the blaze at his brother’s home and found the family of four dead.

“This is the most brutal case I’ve seen in my experience here,” said Gramiccioni, who has served as prosecutor since 2012. He added that if New Jersey had the death penalty, he would seek it in this case.

The prosecutor cited finances as the cause of the killings, but did not elaborate.

Keith Caneiro was the CEO and chief technology officer for Square One, an Asbury Park technology consulting firm. Paul Caneiro was vice president.

Paul Caneiro was charged with four counts of murder, aggravated arson, and weapons possession in the slayings. He was previously charged with aggravated arson in the fire at his home, after his wife and two adult children were forced to escape the blaze.

The quadruple slaying shocked the usually genteel neighborhood in Monmouth County’s horse country. Besides being a bedroom community for wealthy investors and business people from New York, it is home to a number of celebrities, including Bruce Springsteen and Queen Latifah.