FREEHOLD – A co-creator of controversial computer software that analyzed DNA evidence linking Paul Caneiro to the murders of four family members stood behind the technology in court last week, fending off questions about its limitations and flaws for two days.
John Buckleton, chief scientist at the New Zealand Institute of Environmental Science and Research, was in the witness box on November 14 and 15, vouching for the computer software known as STRmix during a hearing to determine whether the DNA evidence it produced was admissible will be at Caneiro’s upcoming trial.
Caneiro, 57, of Ocean Township is charged with the murders of his brother Keith, 50; sister-in-law Jennifer, 45; niece Sophia, 8; and cousin Jesse, 11, at Keith Caneiro’s Colts Neck mansion, where the victim’s bodies were discovered on November 21, 2018.
DNA believed by analysts to be a mixture of Paul and Sophia Caneiro was later found on gloves and a pair of jeans in the basement of the defendant’s home in Ocean Township.
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“Are you satisfied that STRmix is widely accepted in the scientific community,” Monmouth County Deputy First Assistant Prosecutor Christopher Decker asked Buckleton during the Nov. 15 hearing before Superior Court Judge Marc C. Lemieux, the Monmouth County Assignment Judge.
“Yes,” Buckleton replied.
‘Do you have any doubts that STRmix is suitable for handling cases?’ Decker asked the witness.
“No,” Buckleton replied.
The outcome of the hearing on the admissibility of the evidence will have statewide implications for STRmix because, although the New Jersey State Police recently began using the technology in its DNA lab, the computer software has never before been questioned or has been deemed reliable in any New Jersey state. court.
Monmouth County Deputy First Assistant Prosecutor Christopher Decker questions Dr. John Buckleton of New Zealand, co-developer of STRmix and chief scientist at the Institute of Environmental Science and Research, during the pre-trial hearing for Paul Caneiro.
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STRmix deviates from the traditional DNA analysis method of random match probability, which generates a statistic about the probability that a match to a DNA profile can be found in the general population.
Instead, the computer software in question uses a method known as probabilistic genotyping, designed to test small amounts of DNA and complex mixtures that often cannot be analyzed using traditional methods.
Probabilistic genotyping analyzes mixtures to which more than one person has contributed to generate a ‘likelihood ratio’ that a person of interest can be included or excluded as a contributor.
The Public Prosecution Service, which represents Caneiro, disputes the reliability of STRmix. In its challenge, the agency pointed out limitations in the software’s ability to analyze mixtures of DNA from related individuals. It has also alleged that the laboratory that analyzed Caneiro’s DNA evidence did so outside the limits for which the STRmix software had been validated as reliable.
Christopher Godin of the NJ Office of the Public Defender’s Forensic Science Unit discusses a document with John Buckleton, chief scientist of New Zealand’s Institute of Environmental Science and Research, during a pre-trial hearing on November 15 for Paul Caneiro.
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On November 15, Decker confronted Buckleton about so-called “miscodes” in STRmix that defense experts have highlighted in their reports.
Buckleton said there were 15 coding errors, all of which have since been corrected and publicly posted on STRmix’s website. He emphasized that the errors had minimal impact on criminal cases.
Decker pointed out that one of the defense experts wrote in his report that the errors affected 60 criminal cases, with the “likelihood ratio” having to be adjusted in 24 of the cases.
“It caused a relatively small difference in the population reference count,” Buckleton said.
Buckleton went on to say that the critic incorrectly wrote in his report that the error affected thousands of criminal convictions.
“It had no impact on thousands of convictions,” Buckleton testified.
In the 60 cases in question, likelihood ratios were recalculated, and in many cases the result was the same, he said. Buckleton said all the errors were discovered before the trial.
Paul Caneiro listens to testimony Nov. 15 during a pretrial hearing before Superior Court Judge Marc C. Lemieux at the Monmouth County Courthouse in Freehold. The hearing will assess the admissibility of DNA evidence in the quadruple murder case against him.
Christopher Godin of the Public Defender’s Office pressed Buckleton about the errors, pointing out that a majority of criminal cases in the United States never go to trial, but are instead resolved with guilty pleas.
“In those cases, it’s not necessarily likely that someone would find that a bad code affected the DNA evidence in that case,” Godin said.
“Miscodes did not affect the DNA evidence,” Buckleton emphasized. “The miscodes we’ve discovered so far all have a small effect on the numerical values or on some peripheral functionality.”
Godin questioned Buckleton about the limitations of the software to analyze the DNA of family members. He pointed out, and Buckleton agreed, that family members share so-called alleles, which are DNA sequences that a person inherits from each parent.
‘As a result, family members can sometimes deposit DNA that looks as if it comes from another family member?’ Goddess asked.
“Yes,” Buckleton replied.
Superior Court Judge Marc C. Lemieux will preside over a hearing for Paul Caneiro on Nov. 15 at the Monmouth County Courthouse in Freehold.
More: Top judge orders no further delay in the case against Paul Caneiro for murdering the Colts Neck family
Godin suggested to the witness that the DNA analysis in the Caneiro case may have wrongly excluded Keith Caneiro from the DNA profiles in favor of his brother, to the detriment of Paul Caneiro.
“There are exclusions that STRmix has made that are very damaging to Mr. (Paul) Caneiro,” Godin said.
“Absolutely,” Buckleton said.
Authorities allege that Paul Caneiro committed the murders after Keith discovered he was stealing from the companies they co-owned.
The victim’s bodies were discovered by emergency responders responding to a slow-burning fire at the Colts Neck mansion. Keith Caneiro had been shot four times in the head and once in the back. Jennifer Caneiro and the two children were stabbed repeatedly and badly burned. Jennifer was also shot in the head.
Authorities allege that Paul Caneiro set fire to the mansion to cover up the murders, then set his own house on fire to mislead investigators into thinking a violent criminal was targeting the entire family.
Caneiro is expected to stand trial in the case early next year.
The hearing on the DNA evidence is expected to continue on Monday, November 18.
This article originally appeared on Asbury Park Press: Paul Caneiro trial: Expert grilled about the limits of DNA software
