But lately, there had been signs the relationship was unraveling, and Thursday, Paul J. Caneiro, the older of the two, was charged with killing his brother, his sister-in-law and their two young children and setting fire to their $1.6 million home in upscale Colts Neck, New Jersey, just days before Thanksgiving.

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

The bodies were discovered Nov. 20, after Paul Caneiro went to his brother’s house, armed with a knife and a gun, a complaint charged. After the family was dead, he set fire to the house to try to conceal evidence, Gramiccioni said.

Caneiro, 51, had previously been charged with dousing his own home with gasoline, about 12 miles away in Ocean Township, and setting it on fire on the same day his brother, 50-year-old Keith M. Caneiro, was found dead of multiple gunshot wounds outside his burning home. The bodies of the others — Jennifer Caneiro, 45; Jesse, 11; and Sophia, 8 — were found inside.

Officials said they believed the motive was “financial;” they are looking into the brothers’ business ventures and financial dealings as part of the investigation.

In a statement, lawyers for Paul Caneiro said he was innocent. They said Paul Caneiro was a loving brother and uncle who cherished his family and was involved in the lives of his niece and nephew.

Before dawn Nov. 20, Caneiro shot Keith Caneiro at his Colts Neck property, according to the prosecutor’s office. He then shot and stabbed Jennifer Caneiro and stabbed the children before setting a fire in the basement of the house in “an effort to conceal” the evidence, Gramiccioni said. Paul Caneiro returned home and set his own house on fire, the prosecutor said, planning to destroy evidence of his earlier crimes in Colts Neck.

The New York Times

Annie Correal, Tyler Pager and Ashley Southall © 2018 The New York Times