Paul's Ocean Township home went up in flames hours before his brother's.
Prosecutors so far have been mum on a motive - but are set to announce the fresh set of charges against Caneiro at a press conference later Thursday morning.
Gramiccioni says Paul Caneiro shot his brother multiple times on the front lawn of the Willow Brook Road mansion in the early morning hours of November 20.
Police said Paul Caneiro used gasoline to fuel the early morning fire at his two-story Colonial in Ocean Township, about 10 miles from his brother's $1.5 million home in Colts Neck.
A New Jersey man repeatedly shot his brother, fatally stabbed his brother's wife and two young children, and then set their mansion on fire in a familial quadruple homicide, Monmouth County prosecutor Christopher Gramiccioni said Thursday.
The family was found dead Tuesday, Nov. 20, when firefighters responded to a blaze at their Colts Neck home.
The 51-year-old New Jersey resident allegedly used gasoline to set fire to his Ocean Township home before dawn on November 20 while his wife and two daughters were inside, according to an arrest warrant.
An investigation into those businesses - and the financial dealings of the Caneiros - has been launched, the prosecutor said.
In explaining the timeline as to why the Colts Neck fire, which was started in the basement of the sprawling home, was not reported until 12:45 p.m. - almost seven hours after the Ocean fire -Gramiccioni said that it smoldered for a while before it was exposed to oxygen and then began to grow and spread to become visible from outside. Medical examiners had not determined causes of death for them as of midweek.
He said the fire in Ocean Township was also set "for the objective of both destroying evidence of his earlier crimes in Colts Neck and to also create an illusion that the overall Caneiro family was somehow victimized or targeted".
"The fire at his home served two purposes", Gramiccioni said.
Paul Caneiro's attorneys, Robert Honecker and Mitchell Ansell, said in a statement Thursday their client maintained his innocence and that his family "means more to him than anything else in this world".
Clarification: This article has been updated to clarify that Jennifer Caneiro was stabbed and shot, according to the Monmouth County prosecutor. "His family fully support his defense of this charge". Paul and Keith Caneiro are listed as the sole officers of a company that involved the sale and service of computers, New Jersey business records show. "Have no reason to believe that's the case, think it was targeted".