Previously unusable DNA samples entered as evidence in trial of quadruple killings in NJ mansion

The explosive trial of a New Jersey man accused of slaughtering four of his relatives at their mansion six years ago is expected to feature previously unusable DNA samples as evidence, according to a report Friday.

Paul Caneiro, 57 — who’s accused of killing his business partner brother and the sibling’s family in Colts Neck shortly before Thanksgiving 2018 — faced new evidence analyzed by a controversial and cutting-edge genetic tech tool at his pretrial hearing earlier this month.

Known as STRmix, the hotly debated software allows forensic analysts to test DNA samples that likely would have been considered too tiny or complex a decade ago, NBC News reported.

More than a dozen DNA samples that analysts reviewed using STRmix were cited by prosecutors at the Monmouth County hearing — and were challenged by Caneiro’s lawyers, the report said.

The defense attorneys criticized the increasingly common tool, saying it hasn’t been proven reliable like “safety-critical” systems in cars and airplanes have been.

The software could produce flawed results that wrongfully convict someone, Caneiro’s attorneys said.

Prosecutors, meanwhile, argued that STRmix has been tested and tried in labs and courts nationwide.

“The results have been consistent,” prosecutors said in a court filing. “STRmix is not new — it is tried and tested.”

Caneiro is accused of gunning down his brother, Keith, 50,  then fatally shooting and stabbing  his wife, Jennifer, 50,  and stabbing their children, Jesse, 11,  and Sophia, 8,  before setting their sprawling $1.5 million home on fire.

More details about the DNA samples weren’t immediately clear, but investigators said in 2019 that Sophia’s blood was spattered on a pair of Caneiro’s jeans, and that a latex glove and a knife were recovered from his basement after the murder.

Prosecutors have cited money and greed as his motive.

At the hearing this month, one of the makers of the software was called to testify at the pretrial hearing last month, according to a transcript cited by NBC News.

“I don’t want to contribute to an injustice ever,” STRmix developer John Buckleton said in court.

 “[The] motivation is to actually test the software well, try and break it if we can, and, if we miss something, just honestly report what has happened,” STRmix developer John Buckleton said in court.

STRmix’s creators say it helps solve hard-to-analyze DNA samples, such as  ones containing genetic material from up to four people, using a statistical method dubbed “probabilistic genotyping.”

A judge is expected to weigh in on the issue in February, and jury selection will likely begin in March.

Caneiro has pleaded not guilty and his previous lawyers said, “He would never hurt any member of his family.”