The Caneiro family's upscale home 80 kilometres southwest of New York City was set alight by an arsonist. Photo / AP
The Caneiro family's upscale home 80 kilometres southwest of New York City was set alight by an arsonist. Photo / AP
Mystery surrounds the horrific murder of tech millionaire Keith Caneiro, who was found dead with his wife and two young children on Tuesday in what police are calling a "targeted attack".
Mr Caneiro, 50, was shot dead while his wife Jennifer, 45, their son Jesse, 11, and daughter Sophia, 8, were stabbed before their upscale home was set alight in Colts Neck, New Jersey, about 80 kilometres southwest of New York City.
Officials have confirmed the family of four was slain before the devastating inferno tore through the property.
On Wednesday, Mr Caneiro's older brother Paul Caneiro was charged with aggravated arson for an alleged attempt to burn down his own house just hours earlier in Ocean Township, New Jersey.
The elder Mr Caneiro's wife and two adult daughters were inside the home at the time, according to a police document. No one was injured in the predawn blaze, which was reported at 5am on Tuesday.
Paul Caneiro's home is almost 20 kilometres away from his brother's $1.8 million mansion.
A lawyer for the brother defended his client following his arrest, saying he was at home when the family was killed and their property went up in flames.
"He loved him," Robert Honecker Jr. said in an interview. "And he would not do his brother any harm."
Keith Caneiro with his wife Jennifer. Photo / Supplied
The brothers were partners at a technology firm in Asbury Park called Square One.
Authorities have refused to say whether Paul Caneiro is a suspect in the deaths.
The body of Keith Caneiro, President of Square One, was discovered on the front lawn of his four-bedroom home. He reportedly suffered at least two gunshot wounds to the back and head while his family appear to have been stabbed.
Medical examiners have not determined causes of death but said the bodies of Ms Caneiro and her children were badly burned.
Authorities now believe all four of the Caneiros were killed before their mansion was torched.
"My client maintains his innocence on this charge and any other potential charges," Paul Caneiro's lawyer told CNN earlier this week. "His family fully support his defence of this charge. No evidence has been produced that suggests a reason why he would engage in such conduct. He fully expects to be vindicated when this case finally resolves."
There is still no suggested motive for the murders.
Paul Caneiro, 51, has been arrested for setting fire to his own home. Photo / Supplied
All four members of Keith Caneiro's family were "victims of homicidal violence," prosecutors said, adding there was no indication of suicide.
"We believe that in some form of fashion that this family was targeted," Montmouth County Prosecutor Christopher Gramiccioni said, according to the Daily Mail. "If this was an open threat to the community, the first thing we would do is put that information out to the community at large.
"I have no reason to believe that's the case. I have reason to believe this was a targeted case."
A vigil was held for the Caneiro family on Wednesday night in Colts Neck. The town's mayor JP Bartolomeo told mourners: "A lot of people are asking for answers, there's no answers. It's a sad day yesterday.
"As was mentioned on TV, possibly one of the most heinous crimes in the county.
"I'd be lying if I stood here and told you this was easy. We lost four really nice people from our community, who I happened to be friends with, who my boys were friends with, a lot of you were friends with."
