Paul Caneiro's public defender entered the plea on his behalf in court in Monmouth County on Monday.
Prosecutors allege he continued to work and receive income through his wife while collecting disability insurance following a 2012 motor vehicle accident.
Caneiro already faces four counts of murder, along with arson and weapons charges, in the Nov. 20, 2018, deaths of his brother Keith; Keith's wife, Jennifer; their 11-year-old son, Jesse; and their 8-year-old daughter, Sophia.
Caneiro allegedly shot his brother four times in the head and once in the back, stabbed his sister-in-law and the kids before setting fire to the family's home.
He is then alleged to have set fire to his own home in Ocean Township to make it look like the family was being targeted by others.
TIMELINE: Colts Neck family murders
Insurance fraud in New Jersey carries a maximum sentence of 10 years.
Monmouth County Prosecutor Christopher Gramiccioni has said the motive for the killings was related to money after Paul allegedly stole $75,000 from Keith.
Keith Caneiro was 90 percent owner of Squareone Inc., a technology firm, with his brother owning the remaining 10 percent. The brothers were equal owners of a second business, EcoStar Pest Management, both of which were operated out of a single office in Asbury Park.
Money had gone missing from the businesses, and Keith had told Paul he was cutting off his wife from payments.
911 call: Man describes chilling scene of Colts Neck family murder
(The Associated Press contributed to this report.)
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